Overview

Module sc

• Description
• Data Types
• Function Index
• Function Details

Copyright © 2007 - current John Haugeland, All Rights Reserved

Version: 2.5.823

Introduced in: September 14, 2007

Authors: John Haugeland (stonecypher@gmail.com).

Description

This is the 2011 revamp of the erlang portion of the scutil library.

ScUtil (erlang and other languages) is available from its own webpage, or on github. The erlang portion of scutil is a valid OTP application and rebar dependency.

I'm modernizing my library. Originally it got too big, so I split it up. However, that's proven more trouble than it's worth - I often found myself asking whether the thing I wanted was in _math, _correlate, _statistics, _lists, _operators, etc. No more. It's all getting dumped into sc.erl and sc_tests.erl. Prototypes are pushed into sc_prototype.erl; that is code which is either insufficiently tested or unfinished. It's moving to eunit; sc_test is being dumped. I'm taking a lot of the customization stuff out of the generated docs, too. There was always an emphasis on testing, but it's getting taken much more seriously this time. I am also no longer a language novice; I can replace at least some of the naive implementations with marginally less naive ones, break fewer conventions, replicate fewer extant library functions, choose better naming and a more appropriate argument order, et cetera.

This also means I can completely ditch all the remnants of the botched move to packages, provide radically less automation which is radically more effective, and generally do a better job of presenting the actual volume of functionality present here. We can get the coverage tools out. We can run prototypical work in a single separate file, to distinguish quality. Etc.

Generally, this is intended to just be an all around improvement and replacement for the library I was pretty happy with, but which was showing strain.

As always, this work remains open source under the MIT license, because free isn't real unless it's free for everyone. http://scutil.com/license/

ScUtil is free. However, I'd like to know where it's ended up. Therefore, please consider mail to stonecypher@gmail.com with text saying where this went a form of "registration." This is not required.

ScUtil has profited significantly from the donations of time, understanding and code given by a variety of generous friends and strangers. The list of small tweaks would be prohibitive, but significant influence on this library is due the following people, in alphabetical order (the least fair of all generic orderings):

• Alain O'Dea of Concise Software
• Alisdair Sullivan
• Aristid Breitkreuz / [MrN, MisterN]
• Ayrnieu
• Bryon Vandiver of Sublab Research and Design
• Chile
• Dave Murphy / WinterMute
• DizzyD
• Dylan Barrie / PhforSlayer
• Essen
• Fred Hebert / MononcQc
• Geoff Cant / Archaelus
• GrizzlyAdams of The Waffle Iron
• Jeff Katz / Kraln
• Jesper Louis Andersen / jlouis
• John Sensebe of Bargaintuan
• Orbitz
• raleigh
• Richard Carlsson
• Robert Virding
• Steve Stair
• Steve Vinoski
• Torbjörn Törnkvist / Etnt
• Toby Opferman
• Vat Raghavan
• Vladimir Sessikov

Rebar use

Here is a valid dependency rule containing instructions to fetch current sc and the testing dependency PropEr for rebar:

     {deps, [ {proper, ".*", {git, "git://github.com/manopapad/proper.git",              "master"}},
              {sc,     ".*", {git, "git://github.com/StoneCypher/scutil.github.com.git", "master"}} ].

Data Types

bw_rate()

bw_rate() = {Scale::bw_scale(), Rate::float()}

bw_rate - Bandwidth rate - is a rate-in-units-per-time notation for bandwidth measurement, eg {{megabits,day},10.5}.

bw_scale()

bw_scale() = {Unit::atom(), Timescale::atom()}

bw_scale - Bandwidth scale - is a units-per-time notation for bandwidth measurement, eg {megabits,day}.

coord()

coord() = {}

Every member of a coord() is a number(). Represents a coordinate, which may imply a sized cartesian space. Many functions expect integer coordinates; the type does not require them. This type does not define member count. If your function requires a specific count of members, name it, as in a coord2() or coord3().

coord2()

coord2() = {number(), number()}

Represents a coordinate, which may imply a sized rectangle. Many functions expect integer coordinates; the type does not require them.

coord2_list()

coord2_list() = [coord2()]

All members of a coord2_list() must be coord2()s.

coord3()

coord3() = {number(), number(), number()}

Represents a coordinate, which may imply a sized 3d box region. Many functions expect integer coordinates; the type does not require them.

coord3_list()

coord3_list() = [coord3()]

All members of a coord3_list() must be coord3()s.

coord_list()

coord_list() = [{}]

All members of a coord_list() must be coord()s. All member coordinates must be of the same size, though this type does not define what that size is. If your function requires a specific count of members, name it, as in a coord2_list() or coord3_list().

filter_function()

filter_function() = function()

Filter functions are 1ary binary predicates - they accept an argument and return either true or false.

function_or_list()

function_or_list() = function() | list()

grid_size()

grid_size() = coord2() | integer()

Coordinates are the width and height of a (1,1) originated grid; as such, coordinates are of the range [1,X] , [1,Y] inclusive, and returned in the form {A,B}. The integer form implies a square grid.

hexchar()

hexchar() = 0..15

Integer must be in the range $0 - $9, the range $a - $f, or the range $A - $F, all inclusive, for inputs; outputs will always use lower case. Synonym of nybble().

hexstring()

hexstring() = [hexchar()]

All elements of the list must be of type hexchar().

io_list()

io_list() = [byte()]

Every list member of an io_list() must be a byte().

io_list_or_binary()

io_list_or_binary() = io_list() | binary()

It's either an io_list() or a binary(). Duh.

keylist()

keylist() = [{}]

All members of keylists are tuples of two-or-greater arity, and the first element is considered their key in the list. List keys are unique; therefore [{a,1},{b,1}] is a keylist, but [{a,1},{a,1}] is not.

list_of_2ary_tuples()

list_of_2ary_tuples() = [{any(), any()}]

list_of_lists()

list_of_lists(T) = [[T]]

Every member of a list_of_lists(T) is a list(T).

list_of_lists()

list_of_lists() = [[]]

Every member of a list_of_lists() is a list().

list_of_tuples()

list_of_tuples(T) = [{T}]

Every member of a list_of_lists(T) is a tuple(T).

list_of_tuples()

list_of_tuples() = [{}]

Every member of a list_of_lists() is a tuple().

list_or_binary()

list_or_binary() = list() | binary()

It's either a list() or a binary(). Duh.

numeric_list()

numeric_list() = [number()]

All members of a numeric list must be number()s.

numeric_tuple()

numeric_tuple() = {number()}

Every member of a numeric_tuple() must be a number().

nybble()

nybble() = 0..15

Integer must be in the range $0 - $9, the range $a - $f, or the range $A - $F, all inclusive, for inputs; outputs will always use lower case. Synonym of hexchar().

pos_numeric_list()

pos_numeric_list() = [number()]

All members of a numeric list must be number()s. Should enforce positive-ness but don't know how without losing floats.

positive_integer_or_list()

positive_integer_or_list() = pos_integer() | list()

Positive integer or list.

ranking()

ranking(T) = {Ranking::number(), Value::T}

Values are usually number()s, but do not have to be with custom ranking predicates.

ranking()

ranking() = {Ranking::number(), Value::any()}

Values are usually number()s, but do not have to be with custom ranking predicates.

ranking_list()

ranking_list(T) = [ranking(T)]

Members of a rankinglist() must be ranking()s.

ranking_list()

ranking_list() = [ranking()]

Members of a rankinglist() must be ranking()s.

sanitizer()

sanitizer() = [] | filter_function()

Sanitizers are used by sanitize_tokens/2 for input sanitization; they define what parts of an input list are valid, and the remainder are removed. Sanitizers may either be a list of acceptable elements or a filter function.

seven_vector()

seven_vector(T) = [T] | {T, T, T, T, T, T, T}

A seven-vector always has seven elements, so this can be expressed as the alternation {A::number(), B::number(), C::number(), D::number(), E::number(), F::number(), G::number()} | [A::number(), B::number(), C::number(), D::number(), E::number(), F::number(), G::number()].

seven_vector_list()

seven_vector_list(T) = [T]

A seven-vector expressed as a list.

seven_vector_tuple()

seven_vector_tuple(T) = {T, T, T, T, T, T, T}

A seven-vector expressed as a tuple.

sorted_keylist()

sorted_keylist() = keylist()

A sorted keylist is a keylist in the order provided by lists:sort/1. Because of erlang tuple ordering rules and the fact that keylist keys are unique, this means the list will be ordered by key.

string_list()

string_list() = [[]]

Every member of a stringlist() is a string().

three_or_seven_vector()

three_or_seven_vector(T) = three_vector(T) | seven_vector(T)

A three or a seven-vector.

three_vector()

three_vector(T) = [T] | {T, T, T}

A three-vector always has three elements, so this can be expressed as the alternation {A::T(), B::T(), C::T()} | [A::T(), B::T(), C::T()].

three_vector_list()

three_vector_list(T) = [T]

A three-vector expressed as a list.

three_vector_tuple()

three_vector_tuple(T) = {T, T, T}

A three-vector expressed as a tuple.

time12()

time12() = {1..12, 1..60, am | pm}

A human readable 12-hour time

time12s()

time12s() = {1..12, 1..60, 1..60, am | pm}

A human readable 12-hour time, with seconds

time24()

time24() = {0..23, 1..60}

A human readable 24-hour time

time24s()

time24s() = {0..23, 1..60, 1..60}

A human readable 24-hour time, with seconds

timestamp()

timestamp() = {Megaseconds::non_neg_integer(), Seconds::non_neg_integer(), MicroSeconds::non_neg_integer()}

Erlang's timestamp type

type_label()

type_label() = integer | float | list | tuple | binary | bitstring | boolean | function | pid | port | reference | atom | unknown

Used by type_of(), this is just any single item from the list of erlang's primitive types, or the atom unknown.

unit_vector()

unit_vector() = vector()

The hypoteneuse of a unit vector is precisely one unit long. Unit vectors are also called normalized or magnitude-normalized vectors.

vector()

vector(T) = [T] | {T}

Every member element of a vector(T) is a T.

vector()

vector() = [number()] | {number()}

Every member element of a vector() is a number().

vector_list()

vector_list(T) = [vector(T)]

Every member element of a vectorlist(T) is a vector(T).

vector_list()

vector_list() = [vector()]

Every member element of a vectorlist() is a vector().

weight_list()

weight_list(T) = [weighted_value(T)]

All members of weightlists must be weighted_value(T)s.

weight_list()

weight_list() = [weighted_value()]

All members of weightlists must be weighted_value()s.

weighted_value()

weighted_value(T) = {Value::T, Weight::number()}

Used by functions like weighted_arithmetic_mean/1 and from_weighted/1, weighted_value()s represent a value with an associated importance or "weight".

weighted_value()

weighted_value() = {Value::any(), Weight::number()}

Used by functions like weighted_arithmetic_mean/1 and from_weighted/1, weighted_value()s represent a value with an associated importance or "weight".

Function Index

Function Details

absolute_difference/2

Untested Stoch untested Takes the absolute value of the difference between the two arguments. Offered mostly to make dependant code clearer.

  1> sc:absolute_difference(1.25, 1).
  0.25
 
  2> sc:absolute_difference(2,1).
  1
 
  3> sc:absolute_difference(1,2).
  1
 
  4> sc:absolute_difference(1,1).
  0
 
  5> sc:absolute_difference(1,-1).
  2
 
  6> sc:absolute_difference(100,35).
  65

Introduced in: Version 504

abstract_attributes/1

Untested Stoch untested

Introduced in: version 532

abstract_function/2

Untested Stoch untested

Introduced in: version 531

abstract_functions/1

Untested Stoch untested

Introduced in: version 531

additive_factorial/1

Untested Stoch untested

Introduced in: Version 639

adjust_counter_by/2

Adds to a counter's value; if the counter was not already defined, it will become the value in the By argument.

  1> sc:counter_at(hello).
  0
 
  2> sc:inc_counter(hello).
  1
 
  3> sc:adjust_by(hello, 3).
  4

Introduced in: Version 680

alarm_set/3

Untested Stoch untested

Introduced in: Version 515

alarm_terminate/1

Untested Stoch untested

Introduced in: Version 515

all_neighbor_pairs/1

Untested Stoch untested

Introduced in: Version 536

all_neighbor_pairs/2

Untested Stoch untested

Introduced in: Version 536

amean_vector_normal/1

Untested Stoch untested Returns the arithmetic mean of the elements of the unit vector for the vector provided.

Introduced in: Version 497

arithmetic_mean/1

Tested Take the arithmetic mean (often called the average) of a list of numbers.

  1> sc:arithmetic_mean([1,2,3,4,5]).
  3.0
 
  2> sc:arithmetic_mean([]).
  0.0
 
  3> sc:arithmetic_mean([2,2,2,2]).
  2.0
 
  4> sc:arithmetic_mean([-3,2]).
  -0.5

Wolfram Alpha confirms result 1
Wolfram Alpha confirms result 3
Wolfram Alpha confirms result 4

Introduced in: Version 481

See also: amean_vector_normal/1, geometric_mean/1, harmonic_mean/1, weighted_arithmetic_mean/1.

ascii_alphanum_list_subset/1

Introduced in: Version 651

bandwidth_calc/1

Equivalent to bandwidth_calc(Data, all).

Introduced in: Version 478

bandwidth_calc/2

Untested Stoch untested Calculates digital line bandwidth over timescales in converted units.

  1>

  5> sc:bandwidth_calc({10,meg}, {gigabits,day}).
  {{gigabits,day},864.0}

Introduced in: Version 478

benchmark/1

Benchmark a lambda call. os:timestamp/0 is used rather than erlang:now/0 because erlang:now/0 is massaged time - gaps are smoothed, reversals are prevented, reads are forced monotonic increasing, et cetera (thanks MononcQc,) whereas os:timestamp/0 is raw.

  1> Delay1s = fun() -> receive after 1000 -> mississippi end end.
  #Fun<erl_eval.20.21881191>
 
  2> Delay1s().
  mississippi
 
  3> sc:benchmark(Delay1s).
  {1.014,mississippi}
 
  4> {GenTime, Dataset} = sc:benchmark(fun() -> sc:shuffle(lists:seq(1,100000)) end).
  { 0.203,
    [ 51251,43276,49951,60293,85795,53354,81523,80855,35387,
      63856,17466,50722,88409,33148,98511,43668,12019,6187,63052,
      80796,80444,68758,60669,74765,31900,66920,82825 | ... ] }
 
  5> {SortTime, _Sorted} = sc:benchmark(fun() -> lists:sort(Dataset) end).
  { 0.078,
    [ 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,
      23,24,25,26,27 | ... ] }

Introduced in: Version 743

benchmark/2

Introduced in: Version 743

benchmark/3

bin_to_hex_list/1

Untested Stoch untested

Introduced in: Version 640

by_distance/2

Untested Stoch untested

Introduced in: Version 519

by_distance_raw/2

Untested Stoch untested

Introduced in: Version 518

byte_to_hex/1

Untested Stoch untested Convert a byte() into a hexstring(). The hexstring() result will always be two characters (left padded with zero if necessary).

  1> sc:byte_to_hex(7).
  "07"
 
  2> sc:byte_to_hex(255).
  "ff"

Introduced in: Version 571

caspers_jones_estimate/1

Untested Stoch untested See

Introduced in: Version 478

ceil/1

Equivalent to ceiling(X).

Introduced in: Version 510

ceiling/1

Tested Returns the ceiling (round towards positive infinity) of a float.

  1> sc:ceil(0.5).
  1
 
  2> sc:ceil(0).
  0
 
  3> sc:ceil(0.0).
  0
 
  4> sc:ceil(1.0).
  1
 
  5> sc:ceil(-1.0).
  -1
 
  6> sc:ceil(-1.5).
  -1
 
  7> sc:ceil(-1).
  -1
 
  8> sc:ceil(1).
  1

Introduced in: Version 510

central_moment/2

BUGGY Untested Stoch untested Takes the Nth cetral moment of a list. The Nth central moment of a list is the arithmetic mean of (the list items each minus the mean of the list, each taken to the Nth power). In a sense, this is the "normalized" moment. Fractional Ns are not defined. Not to be confused with moment/2. Thanks to Kraln and Chile for straightening me out on moments and central moments.

  1> sc:central_moment([1,1,1], 2).
  0.0
 
  2> sc:central_moment([2,2,2], 2).
  0.0
 
  3> sc:central_moment([1,2,3], 2).
  0.666666666666666
 
  4> sc:central_moment([1,2,3], 3).
  0.0

Introduced in: Version 492

central_moments/1

Equivalent to [central_moment(List, N) || N <- [2, 3, 4]].

Untested Stoch untested

Introduced in: Version 492

central_moments/2

Equivalent to [central_moment(List, N) || N <- Moments].

Untested Stoch untested

Introduced in: Version 492

centroid/1

Untested Stoch untested Calculates the coordinate which represents the per-axis arithmetic mean of a set of points. Convenient in list comprehensions. To calculate the centroid of [1,1], [2,3], you gather the X coordinates [1,2], then use their mean 1.5; then do the same for the Y, [1,3] to 2. The centroid would thus be [1.5,2]. You may pass any number of coordinates to this function, of any axis count, but they must all be the same axis count. The return value will be a coordinate with the same axis count. Negative and real values are fine; imaginary math is not implemented.

  1> sc:centroid([[1]]).
  [1.0]
 
  2> sc:centroid([[1,1],[2,2]]).
  [1.5,1.5]
 
  3> sc:centroid([[1,1,1],[2,2,2],[3,3,3]]).
  [2.0,2.0,2.0]
 
  4> sc:centroid([[1,-1,1.0],[-2,-2,-2],[3,3,3],[4,4,4],[5,5,5]]).
  [2.2,1.8,2.2]

Introduced in: Version 516

circ_within_origin_circ/2

Untested Stoch untested

circles_contact/2

Untested Stoch untested

circles_overlap/2

Untested Stoch untested

columnate/1

Equivalent to columnate(List, 2, 3).

Introduced in: Version 734

columnate/2

Introduced in: Version 734

columnated_rows/2

Introduced in: Version 731

columnated_text/2

Introduced in: Version 735

columns/2

Introduced in: Version 730

combinations/2

Stoch untested Provides a list of every unique combination of input terms, order-ignorant; contrast permute/2. Permutations are all unique combinations of a set of tokens; the 2-permutations of [a,b,c] for example are [a,b], [a,c] and [b,c]. Note the absence of other orderings, such as [b,a], which are provided by permute/2. Combinations are taken of a smaller count of tokens than the main set. Combinations are not ordered, but this implementation happens to provide answers in the same order as the input list. Mixed-type lists are safe; items are shallow evaluated, meaning that sublists within the list are treated as single elements, and will neither be rearranged nor will have elements selected from within them.

  1> sc:combinations(2, [a,b,c,d]).
  [ [a,b], [a,c], [a,d], [b,c], [b,d], [c,d] ]
 
  2> sc:combinations(2, ["dave","kate","pat"]).
  [ ["dave","kate"], ["dave","pat"], ["kate","pat"] ]
 
  3> sc:combinations(2, [fast, strong, smart, lucky]).
  [ [ fast,   strong ],
    [ fast,   smart  ],
    [ fast,   lucky  ],
    [ strong, smart  ],
    [ strong, lucky  ],
    [ smart,  lucky  ] ]

Introduced in: Version 473

count_bits/1

Incomplete Untested Stoch untested Counts the number of bits turned on in a sufficiently sized unsigned two's compliment integer representation of Num.

  1> sc:count_bits(5).
  2

Introduced in: Version 727

count_of/2

Untested Stoch untested Counts the number of instances of Item in List.

  1> TestData = lists:duplicate(40, [healthy, nonsmoker] ) ++
                lists:duplicate(10, [healthy, smoker]    ) ++
                lists:duplicate(7,  [cancer,  nonsmoker] ) ++
                lists:duplicate(3,  [cancer,  smoker]    ).
 
  [[healthy,nonsmoker], [healthy,nonsmoker], [healthy|...], [...]|...]
 
  2> sc:count_of([healthy,smoker], TestData).
  10
 
  3> sc:count_of([healthy,nonsmoker], TestData).
  40

Introduced in: Version 550

counter_at/1

Checks a counter's value; if the counter was not already defined, it will report zero.

  1> sc:counter_at(hello).
  0
 
  2> sc:inc_counter(hello).
  1
 
  3> sc:inc_counter(hello).
  2
 
  4> sc:inc_counter(hello).
  3
 
  5> sc:counter_at(hello).
  3
 
  6> sc:reset_counter(hello).
  0
 
  7> sc:counter_at(hello).
  0

Introduced in: Version 682

country_codes/0

Introduced in: Version 653

cross_product/2

Incomplete Untested Stoch untested Calculates the cross product of two vectors (Incomplete represented as three_vector()s - no support yet for seven).

  1> sc:dot_product([1,1,1],[2,2,2]).
  6
 
  2> sc:dot_product([1,1,1],[3,3,3]).
  9
 
  3> sc:dot_product([-1,0,1],[3,3,3]).
  0
 
  4> sc:dot_product([-1,1,1],[3,3,3]).
  3
 
  5> sc:dot_product([0.5,1,2],[1,1,1]).
  3.5

Introduced in: Version 80

cube/1

Untested Stoch untested Cubes the input; convenient in list comprehensions to prevent recalculation, and clear in the fashion of documentary functions.

  1> sc:cube(2).
  8
 
  2> sc:cube(2.5).
  6.25

Introduced in: Version 508

dec_counter/1

Equivalent to adjust_counter_by(Name, -1).

Introduced in: Version 681

dec_counter/2

Equivalent to adjust_counter_by(Name, -1 * By).

Introduced in: Version 681

differences/1

Untested Stoch untested

Introduced in: Version 547

distinct_neighbor_pairs/1

Untested Stoch untested

Introduced in: Version 535

distinct_neighbor_pairs/2

Untested Stoch untested

Introduced in: Version 535

dot_product/2

Incomplete Untested Stoch untested Calculates the dot product of two vectors (Incomplete represented as numeric lists; tuples not yet supported).

  1> sc:dot_product([1,1,1],[2,2,2]).
  6
 
  2> sc:dot_product([1,1,1],[3,3,3]).
  9
 
  3> sc:dot_product([-1,0,1],[3,3,3]).
  0
 
  4> sc:dot_product([-1,1,1],[3,3,3]).
  3
 
  5> sc:dot_product([0.5,1,2],[1,1,1]).
  3.5

Introduced in: Version 80

dstat/2

Untested Stoch untested Return descriptive statistics of a numeric list. nspired by J dstat from bbot.org. J seems to be assuming sample for statistics. I do not like assumptions.

Introduced in: Version 487

dstat_ex/2

Untested Stoch untested Return extended descriptive statistics of a numeric list. nspired by J dstat from bbot.org. J seems to be assuming sample for statistics. I do not like assumptions.

Introduced in: Version 487

elements/2

Untested Stoch untested

Introduced in: Version 546

elements/3

Untested Stoch untested

elements/4

Untested Stoch untested

ensure_started/1

Equivalent to ensure_started(App, []).

Introduced in: Version 758

ensure_started/2

Introduced in: Version 770

entrypoints/1

Untested Stoch untested

Introduced in: Version 530

entrypoints/2

Untested Stoch untested

Introduced in: Version 530

euclidean_distance/2

Untested Stoch untested Returns the distance between two coordinates in any N-space. In two dimensions, this is known as the Pythagorean theorem. The coordinates may be of any positive integer dimensionality (2d, 3d, but no -1d or 2.5d), but both coordinates must be of the same dimensionality. The coordinates may have real-valued or negative components, but imaginary math is not implemented. This function tolerates tuple coordinates by converting them to lists; list coordinates are thus slightly faster.

  1> sc:distance([0,0],[1,1]).
  1.4142135623730951
 
  2> sc:distance({0,0},[-1,1.0]).
  1.4142135623730951
 
  3> sc:distance([0,0,0,0],[1,-1,1,-1]).
  2.0

Introduced in: Version 575

eval/1

DANGEROUS Untested Stoch untested modified from http://www.trapexit.org/String_Eval

Introduced in: Version 556

eval/2

DANGEROUS Untested Stoch untested from http://www.trapexit.org/String_Eval

Introduced in: Version 556

even_or_odd/1

Documentary convenience function (synonymous with parity/1) that returns the atoms even or odd for any integer.

  1> sc:even_or_odd(3).
  odd

Introduced in: Version 489

every_flag_representation/1

Untested Stoch untested Returns every interpretation of the list as a set of boolean flags, including all-off and all-on.

  1> sc:every_flag_representation([1,2,3,4]).
  [ [], [4], [3], [3,4], [2], [2,4], [2,3], [2,3,4], [1], [1,4], [1,3], [1,3,4], [1,2], [1,2,4], [1,2,3], [1,2,3,4] ]
 
  2> length(sc:every_flag_representation(lists:seq(1,16))).
  65536
 
  3> SourceOfPowers = sc:every_flag_representation([magic,technology,evil,alien]).
  [[],                              % Batman
   [alien],                         % Superman
   [evil],                          % Darkseid
   [evil,alien],                    % Sinestro
   [technology],                    % Mister Terrific (Michael Holt)
   [technology,alien],              % The Blue Beetle
   [technology,evil],               % The OMACs
   [technology,evil,alien],         % Braniac
   [magic],                         % Shazam
   [magic,alien],                   % Green Lantern (Alan Scott)
   [magic,evil],                    % Lucifer Morningstar
   [magic,evil,alien],              % pre-crisis Star Sapphire
   [magic,technology],              % Alexander Luthor Jr.
   [magic,technology,alien],        % Mister Miracle
   [magic,technology,evil],         % pre-crisis Sinestro
   [magic,technology,evil,alien]]   % Granny Goodness

Introduced in: Version 552

every_member_representation/1

Equivalent to every_member_representation(Memberships, no_absence).

Untested Stoch untested

every_member_representation/2

Untested Stoch untested For a list of memberships, return every possible combination of one representative member from each list. The parameter AllowAbsence controls whether memberships may be unrepresented; if unrepresented memberships are possible, then one possible representation becomes the empty list.

  1> sc:every_member_representation([ [a,b],[1,2,3],[i,ii,iii] ], no_absence).
  [[a,1,i], [a,1,ii], [a,1,iii], [a,2,i], [a,2,ii], [a,2,iii], [a,3,i], [a,3,ii], [a,3,iii], [b,1,i], [b,1,ii], [b,1,iii], [b,2,i], [b,2,ii], [b,2,iii], [b,3,i], [b,3,ii], [b,3,iii]]
 
  2> sc:every_member_representation([ [a,b],[1,2],[i,ii] ], allow_absence).
  [ [], [i], [ii], [1], [1,i], [1,ii], [2], [2,i], [2,ii], [a], [a,i], [a,ii], [a,1], [a,1,i], [a,1,ii], [a,2], [a,2,i], [a,2,ii], [b], [b,i], [b,ii], [b,1], [b,1,i], [b,1,ii], [b,2], [b,2,i], [b,2,ii] ]
 
  3> Format = fun(Person, Place, Weapon) -> "It was " ++ Person ++ " in the " ++ Place ++ " with the " ++ Weapon ++ "!" end.
  #Fun<erl_eval.18.105910772>
 
  4> { People, Places, Weapons } = { ["Col. Mustard", "Mr. Green"], ["the billiards room", "the kitchen"], ["a lead pipe", "a knife", "a gun"] }.
  {["Col. Mustard","Mr. Green"],
   ["the billiards room","the kitchen"],
   ["a lead pipe","a knife","a gun"]}
 
  5> Places.
  ["the billiards room","the kitchen"]
 
  6> Format("Mrs. Scarlett", "the observatory", "a noose").
  "It was Mrs. Scarlett in the the observatory with the a noose!"
 
  7> EveryClueOutcome = [ Format(ThisPerson, ThisPlace, ThisWeapon) || ThisPerson <- People, ThisPlace <- Places, ThisWeapon <- Weapons ].
  ["It was Col. Mustard in the the billiards room with the a lead pipe!",
   "It was Col. Mustard in the the billiards room with the a knife!",
   "It was Col. Mustard in the the billiards room with the a gun!",
   "It was Col. Mustard in the the kitchen with the a lead pipe!",
   "It was Col. Mustard in the the kitchen with the a knife!",
   "It was Col. Mustard in the the kitchen with the a gun!",
   "It was Mr. Green in the the billiards room with the a lead pipe!",
   "It was Mr. Green in the the billiards room with the a knife!",
   "It was Mr. Green in the the billiards room with the a gun!",
   "It was Mr. Green in the the kitchen with the a lead pipe!",
   "It was Mr. Green in the the kitchen with the a knife!",
   "It was Mr. Green in the the kitchen with the a gun!"]

Introduced in: Version 551

expand_labels/1

Stoch untested Expands a series of labels over lists to create a cartesian 2-ary tuple expansion.

  1> sc:expand_labels([{villain,[lex_luthor,sinistar,gargamel]}]).
  [{villain,lex_luthor},{villain,sinistar},{villain,gargamel}]
 
  2> sc:expand_labels([ {hero,[superman,tinyship,papa_smurf]}, {villain,[lex_luthor,sinistar,gargamel]} ]).
  [{hero,superman},
   {hero,tinyship},
   {hero,papa_smurf},
   {villain,lex_luthor},
   {villain,sinistar},
   {villain,gargamel}]

Introduced in: Version 474

expected_value/1

Stoch untested Returns the expected value of infinite selection from a weighted numeric list. Elements of the list may either be numbers or tuples in the form {Value,Weight} (weight may be floating-point). This means that [ 1,1,1, 10,10 ] and [ {1,3}, {10,2} ] are the same list. The expected value of an empty list is undefined, and will throw badarith. This includes zero-weighted tuple form (example 6.)

  1> sc:expected_value([1,2,3,4,5,6]).
  3.50000
 
  2> sc:expected_value([ {1,5}, {10,1} ]).
  2.5
 
  3> sc:expected_value([ 1,1,1,1,1, {10,1} ]).
  2.5
 
  4> sc:expected_value([ {1,8}, {-1,7} ]).
  0.06666666666666667
 
  5> catch sc:expected_value([ ]).
  {'EXIT',{badarith,[{sc,expected_value,3},
                     {erl_eval,do_apply,5},
                     {erl_eval,expr,5},
                     {shell,exprs,7},
                     {shell,eval_exprs,7},
                     {shell,eval_loop,3}]}}
 
  6> catch sc:expected_value([ {1,0}, {2,0} ]).
  {'EXIT',{badarith,[{sc,expected_value,3},
                     {erl_eval,do_apply,5},
                     {erl_eval,expr,5},
                     {shell,exprs,7},
                     {shell,eval_exprs,7},
                     {shell,eval_loop,3}]}}

Wolfram Alpha confirms result 1
Wolfram Alpha confirms result 2
Wolfram Alpha confirms result 4

Introduced in: Version 502

explode/2

Stoch untested Split any list by any other list, typically a string by a substring. The seperator list must not be empty.

  1> sc:explode(",", "1,2,5,10,20").
  ["1","2","5","10","20"]
 
  2> sc:explode(" ", "John Jacob Jingleheimer Schmidt").
  ["John","Jacob","Jingleheimer","Schmidt"]
 
  3> sc:explode("; ", "North; East; South; West").
  ["North","East","South","West"]
 
  4> sc:explode("No such delimiter", "I am the monarch of the sea").
  ["I am the monarch of the sea"]
 
  5> sc:explode(",", ",,").
  ["", "", ""]
 
  6> sc:explode([beta], [alpha, beta, gamma, delta, beta, epsilon]).
  [[alpha],[gamma,delta],[epsilon]]
 
  7> catch sc:explode([], [alpha, beta, gamma, delta, beta, epsilon]).
  {'EXIT',{badarg,[{sc,explode,2},
                   {erl_eval,do_apply,5},
                   {erl_eval,expr,5},
                   {shell,exprs,7},
                   {shell,eval_exprs,7},
                   {shell,eval_loop,3}]}}
 
  8> catch sc:explode(beta, [alpha, beta, gamma, delta, beta, epsilon]).
  {'EXIT',{badarg,[{sc,explode,2},
                   {erl_eval,do_apply,5},
                   {erl_eval,expr,5},
                   {shell,exprs,7},
                   {shell,eval_exprs,7},
                   {shell,eval_loop,3}]}}

Introduced in: Version 622

explode/3

Untested Stoch untested

Introduced in: Version 622

extrema/1

Tested Returns the lowest and highest values in a list of one or more member in the form {Lo,Hi}. Undefined over the empty list. Mixed-type safe; sorts according to type order rules.

  1> sc:extrema([1,2,3,4]).
  {1,4}
 
  2> sc:extrema([1,2,3,a,b,c]).
  {1,c}

3> sc:extrema( [] ). ** exception error: no function clause matching sc:extrema([])'''

Introduced in: Version 460

factorial/1

Untested Stoch untested

Introduced in: Version 509

factorize/1

Untested Stoch untested Generates a list of the factors of an integer. Not an awesome implementation. Thanks for noticing that I was repeating sqrt unnecessarily, Forest.

file_to_binary_literal_as_string/1

Introduced in: Version 661

first_difference/1

Untested Stoch untested

Introduced in: Version 547

first_pos/2

Untested Stoch untested Finds the 1-offset index of the first item in the list which passes the given predicate, or returns false if none pass.

  1> sc_lists:first_pos([a,b,c,d,2,f],fun erlang:is_integer/1).
  5
 
  2> sc_lists:first_pos([a,b,c,d,e,f],fun erlang:is_integer/1).
  false

Introduced in: Version 539

first_pos/3

Untested Stoch untested Finds the 1-offset index of the first item in the list which passes the given predicate, or returns a default value if none is found. See first_pos/2 for details.

first_row/1

Introduced in: Version 733

fk_readability/3

Untested Stoch untested Calculate the Flesch-Kincaid readability score of a set of text metrics. See Wikipedia and readabilityformulas.com.

Introduced in: Version 706

fk_readability/4

Untested Stoch untested Calculate the Flesch-Kincaid readability score of a block of text. Also takes three lambdas to do text parsing. @see http://en.wikipedia.org/wiki/Flesch-Kincaid_Readability_Test

Introduced in: Version 708

flag_sets/1

Stoch untested Returns every interpretation of the list as a set of boolean flags, including all-off and all-on.

  1> sc:flag_sets([1,2,3,4]).
  [ [], [4], [3], [3,4], [2], [2,4], [2,3], [2,3,4], [1], [1,4], [1,3], [1,3,4], [1,2], [1,2,4], [1,2,3], [1,2,3,4] ]
 
  2> length(sc:flag_sets(lists:seq(1,16))).
  65536
 
  3> sc:flag_sets([]).
  [ [] ]
 
  4> SourceOfPowers = sc:flag_sets([magic,technology,evil,alien]).
  [[],                              % Batman
   [alien],                         % Superman
   [evil],                          % Darkseid
   [evil,alien],                    % Sinestro
   [technology],                    % Mister Terrific (Michael Holt)
   [technology,alien],              % The Blue Beetle
   [technology,evil],               % The OMACs
   [technology,evil,alien],         % Braniac
   [magic],                         % Shazam
   [magic,alien],                   % Green Lantern (Alan Scott)
   [magic,evil],                    % Lucifer Morningstar
   [magic,evil,alien],              % pre-crisis Star Sapphire
   [magic,technology],              % Alexander Luthor Jr.
   [magic,technology,alien],        % Mister Miracle
   [magic,technology,evil],         % pre-crisis Sinestro
   [magic,technology,evil,alien]]   % Granny Goodness

Introduced in: Version 465

floor/1

Tested Takes the floor (round towards negative infinity) of a number. This is different than erlang:trunc/1, which removes the mantissa, in its handling of negative numbers: trunc diminishes towards zero, not towards negative infinity (note examples 6 and 7 below.)

  1> sc:floor(0.5).
  0
 
  2> sc:floor(0).
  0
 
  3> sc:floor(0.0).
  0
 
  4> sc:floor(1.0).
  1
 
  5> sc:floor(-1.0).
  -1
 
  6> sc:floor(-1.5).
  -2
 
  7> erlang:trunc(-1.5).
  -1
 
  8> sc:floor(-1).
  -1
 
  9> sc:floor(1).
  1

Introduced in: Version 511

function_point_count/1

Untested Stoch untested

Introduced in: Version 525

function_stats/1

Untested Stoch untested

Introduced in: Version 524

gen_docs/0

Equivalent to gen_docs("/projects/github/scutil.github.com", "/projects/github/scutil.github.com/erl/doc").

(not testworthy) Generates library documentation using the paths appropriate for the author's PC; you almost certainly want gen_docs/2 instead.

  1> sc:gen_docs().
  ok

Introduced in: 458

gen_docs/2

(not testworthy) Generates library documentation from and to the specified paths WhereIsSrc and WhereToPutDocs respectively. Do not use trailing slashes. Windows paths are okay; remember to double your backslashes, as backslashes in strings need to be quoted.

  1> sc:gen_docs("/projects/scutil", "/projects/scutil/erl/src/docs").
  ok

Introduced in: 458

geometric_mean/1

Tested Take the geometric mean of a list of numbers.

  1> sc:geometric_mean([1,2,3,4,5]).
  2.6051710846973517
 
  2> sc:geometric_mean([2,2,2]).
  2.0
 
  3> sc:geometric_mean([3]).
  3.0
 
  4> sc:geometric_mean([1,10,100]).
  10.000000000000002

Wolfram Alpha confirms result 1
Wolfram Alpha confirms result 2
Wolfram Alpha confirms result 3
Wolfram Alpha confirms result 3

The geometric mean is not defined for lists including 0. This implementation does not handle the geometric mean of lists including negative numbers.

The naive approach geometric_mean(List) -> math:pow(sc:list_product(List), 1/length(List)) is not used because it accumulates error very quickly, and is as such unsuited to huge lists. This is the same as the expected function nth-root(prod, 1/n), but calculated differently for machine reasons.'''

Unit, doc and stochastic (all results are floats, all results between extrema) tested.

Introduced in: Version 482

See also: arithmetic_mean/1, gmean_vector_normal/1, harmonic_mean/1.

get_linked_processes/0

Untested Stoch untested

Introduced in: Version 617

gmean_vector_normal/1

Untested Stoch untested Returns the geometric mean of the elements of the unit vector for the vector provided.

Introduced in: Version 498

grid_scatter/2

Untested Stoch untested Return a Count-length list of non-repeating coordinates in a grid of specified size; useful for feature generation.

Introduced in: Version 599

halstead_complexity/4

Untested Stoch untested

Introduced in: Version 564

halstead_complexity/5

Untested Stoch untested

Introduced in: Version 564

harmonic_mean/1

Untested Stoch untested Take the harmonic mean of a list of numbers.

  1> sc:harmonic_mean([1,2,3,4,5]).
  2.18978102189781

WolframAlpha Confirms

The harmonic mean is not defined for lists including 0.

Introduced in: Version 483

See also: arithmetic_mean/1, geometric_mean/1, hmean_vector_normal/1.

has_bit/2

Incomplete Untested Stoch untested Checks whether a given bit is on in a sufficiently sized unsigned two's compliment integer representation of Num.

  1> sc:has_bit(5,0).
  true
 
  2> scutil:has_bit(5,1).
  false

Introduced in: Version 727

hex_to_int/1

Untested Stoch untested Convert a hexstring() or hexchar() into its numeric value.

  1> sc:hex_to_int("c0ffEE").
  12648430
 
  2> sc:hex_to_int($e).
  14
 
  3> sc:hex_to_int("100").
  256

Introduced in: Version 572

histograph/1

Untested Stoch untested Takes a histograph count of the items in the list. Mixed type lists are safe. Input lists do not need to be sorted. The histograph is shallow - that is, the histograph of [ [1,2], [1,2], [2,2] ] is [ {[1,2],2}, {[2,2],1} ], not [ {1,2}, {2,4} ].

  1> sc:histograph([1,2,a,2,b,1,b,1,b,2,a,2,2,1]).
  [{1,4},{2,5},{a,2},{b,3}]
 
  2> sc:histograph([ sc:rand(10) || X <- lists:seq(1,100000) ]).
  [{0,10044}, {1,9892}, {2,10009}, {3,10016}, {4,10050}, {5,10113}, {6,9990}, {7,9994}, {8,10004}, {9,9888}]
 
  3> ChessBoard = [ rook,  knight, bishop, king,  queen, bishop, knight, rook,
                    pawn,  pawn,   pawn,   pawn,  pawn,  pawn,   pawn,   pawn,
                    empty, empty,  empty,  empty, empty, empty,  empty,  empty,
                    empty, empty,  empty,  empty, empty, empty,  empty,  empty,
                    empty, empty,  empty,  empty, empty, empty,  empty,  empty,
                    empty, empty,  empty,  empty, empty, empty,  empty,  empty,
                    pawn,  pawn,   pawn,   pawn,  pawn,  pawn,   pawn,   pawn,
                    rook,  knight, bishop, king,  queen, bishop, knight, rook ].
  [rook,knight,bishop,king,queen,bishop,knight,rook,pawn,pawn,
   pawn,pawn,pawn,pawn,pawn,pawn,empty,empty,empty,empty,empty,
   empty,empty,empty,empty,empty,empty,empty,empty|...]
 
  4> sc:histograph(ChessBoard).
  [ { bishop, 4  },
    { empty,  32 },
    { king,   2  },
    { knight, 4  },
    { pawn,   16 },
    { queen,  2  },
    { rook,   4  } ]

Introduced in: Version 496

hmac/3

Untested Stoch untested Shorthands for algorithms so you don't need to know block sizes.

Introduced in: Version 646

hmac/4

Semi-Untested An implementation of RFC 2104, HMAC generic hash extension for any hash function and any key size.

The reason this exists is to bring HMAC access to any hashing algorithm, as was the RFC's purpose. There are HMAC functions in Erlang's crypto: module, but they are bound to specific hashers which are beginning to show their age, and they fix block size.

The block size should be at most the block size of the hashing algorithm, but may be reduced (to the detriment of the safety of the result.) Ideally, the block size should be the same as the hashing algorithm's block size, but many systems use variously truncated block sizes, so we support them all. Jerks.

This implementation was

  1> sc:bin_to_hex_list(sc:hmac(fun erlang:md5/1, "hello", "world", 64)).
  "0e2564b7e100f034341ea477c23f283b"
 
  2> sc:bin_to_hex_list(crypto:md5_mac("hello","world")).
  "0e2564b7e100f034341ea477c23f283b"
 
  C:\Users\John>php
  <?php /* php api is reversed of erlang's */
    echo hash_hmac('md5', 'world','hello');
  ?> ^Z
  0e2564b7e100f034341ea477c23f283b
 
  % Also, one of the RFC test sets
 
  3> sc:bin_to_hex_list(sc:hmac(fun erlang:md5/1, "Jefe", "what do ya want for nothing?", 64)).
  "750c783e6ab0b503eaa86e310a5db738"
 
  4> sc:bin_to_hex_list(crypto:md5_mac("Jefe", "what do ya want for nothing?")).
  "750c783e6ab0b503eaa86e310a5db738"
 
  C:\Users\John>php
  <?php echo hash_hmac('md5', 'what do ya want for nothing?', 'Jefe'); ?> ^Z
  750c783e6ab0b503eaa86e310a5db738

Introduced in: Version 645

hmac_md4/2

Obsolete - legacy support only - do not use in new code Untested Stoch untested HMAC wrapper built around MD4 as the core hash, frequently known as hmac-md4 or md4-hmac.

Introduced in: Version 647

hmac_md5/2

Obsolete - legacy support only - do not use in new code Untested Stoch untested HMAC wrapper built around MD5 as the core hash, frequently known as hmac-md5 or md5-hmac.

Introduced in: Version 647

hmac_sha1/2

Should be obsolete, but Erlang's standard library does not include SHA-2, and neither does scutil (yet) - Untested Stoch untested HMAC wrapper built around SHA1-160 (the only SHA-1) as the core hash, frequently known as hmac-sha1, hmac-sha or sha1-hmac.

Introduced in: Version 647

hmean_vector_normal/1

Untested Stoch untested Returns the harmonic mean of the elements of the unit vector for the vector provided.

Introduced in: Version 499

implode/2

Stoch untested Append strings with separating string inbetween - contrast explode/2.

  1> sc:implode(",", ["a", "b", "c"]).
  "a,b,c"
 
  2> sc:implode(",", ["ab", "cd", "ef"]).
  "ab,cd,ef"
 
  3> sc:implode(",", ["", "", ""]).
  ",,"
 
  4> sc:implode("-wop ", ["do", "do", "do"]).
  "do-wop do-wop do"
 
  5> sc:implode("", ["", "", ""]).
  []

Introduced in: Version 621

in_range/3

Introduced in: Version 649

inc_counter/1

Equivalent to adjust_counter_by(Name, 1).

Introduced in: Version 681

inc_counter/2

Equivalent to adjust_counter_by(Name, By).

Introduced in: Version 681

index_of_first/2

Tested Returns the index of the first instance of Item in the List, or undefined if Item is not present.

  1> sc:index_of_first(c, [a,b,c,d,e]).
  3
 
  2> sc:index_of_first(j, [a,b,c,d,e]).
  undefined

Introduced in: Version 463

integer_to_radix_list/2

Untested Stoch untested Convert a number to a radix string using a radix list of your specification and any size. When appropriate, prefer the system provided erlang:integer_to_list/2. Lists are accepted, but converted to tuples before use, so are inefficient.

  1> sc_convert:integer_to_radix_list(1111, "0123456789abcdef").
  "457"
 
  2> sc_convert:integer_to_radix_list(1111, "0123456789").
  "1111"
 
  3> sc_convert:integer_to_radix_list(1234567890, "abcdefghij").
  "bcdefghija"
 
  4> sc_convert:integer_to_radix_list(12648430, {$0, $1, $2, $3, $4, $5, $6, $7, $8, $9, $A, $B, $C, $D, $E, $F}).
  "C0FFEE"
 
  5> sc_convert:integer_to_radix_list(1234567890, [alpha, beta, gamma, delta, epsilon, zeta, eta, theta, kappa, lambda]).
  [beta,gamma,delta,epsilon,zeta,eta,theta,kappa,lambda,alpha]

Introduced in: Version 566

io_list_to_hex_string/1

Untested Stoch untested Convert an io_list() to a hexstring().

  1> sc:io_list_to_hex_string("a").
  "61"
 
  2> sc:io_list_to_hex_string("a08n408nbqa").
  "6130386e3430386e627161"

Introduced in: Version 569

is_between/3

Introduced in: Version 685

is_between/4

Introduced in: Version 685

is_numeric_char/1

Introduced in: Version 737

is_numeric_char/2

is_numeric_string/1

Untested Stoch untested

Introduced in: Version 625

is_numeric_string/2

Untested Stoch untested

Introduced in: Version 625

is_postfix/2

Untested Stoch untested

Introduced in: Version 543

is_repeated_list/1

Introduced in: Version 650

is_sorted_list/1

Untested Stoch untested Returns true if the list is sorted; false otherwise. List sortedness is typesafe, and defined equivalently to how defined by the language and lists:sort().

  1> sc:is_sorted_list([1,2,3]).
  true
 
  2> sc:is_sorted_list([1,2,3,1]).
  false
 
  3> sc:is_sorted_list([1,2,3,false]).
  true
 
  4> sc:is_sorted_list([false,1,2,3]).
  false

Introduced in: Version 514

is_unique_list/1

Untested Stoch untested Returns true if the list is unique; false otherwise. List uniqueness is defined as whether any member of the list compares equally to any other member; deep list inspection is not performed. Comparison is type-safe.

  2> sc:is_unique_list([1,2,3]).
  true
 
  2> sc:is_unique_list([1,2,3,1]).
  false
 
  3> sc:is_unique_list([1,2,3,{1}]).
  true
 
  4> sc:is_unique_list([1,2,3,[1]]).
  true
 
  5> sc:is_unique_list([1,2,3,[1],[1]]).
  false

Introduced in: Version 514

isolate_waveform/1

Untested Stoch untested Remove the baseline of a dataset, normalizing a waveform or other signal to its bottom peak.

Introduced in: Version 716

kendall_correlation/1

Untested Stoch untested Compute the Kendall Tau Rank Correlation Coefficient of a list of coordinate tuples.

  1> sc:kendall([ {1,1}, {2,2}, {3,3}, {4,4}, {5,5} ]).
  {tau,1.0}
 
  2> sc:kendall([ {1,5}, {2,4}, {3,3}, {4,2}, {5,1} ]).
  {tau,-1.0}
 
  3> sc:kendall([ {1,3}, {2,3}, {3,3}, {4,3}, {5,3} ]).
  {tau,1.0}
 
  4> sc:kendall([ {1,2}, {2,2.5}, {3,3}, {4,3.5}, {5,4} ]).
  {tau,1.0}
 
  5> sc:kendall([ {1,2}, {2,2.4}, {3,3}, {4,3.6}, {5,4} ]).
  {tau,1.0}

Introduced in: Version 557

kendall_correlation/2

Equivalent to kendall(lists:zip(List1, List2)).

key_cluster/2

Untested Stoch untested

key_duplicate/1

Tested Iterates a list of {Count,Term}, producing a list of [Term,Term,...].

  1> sc:key_duplicate([ {3,bork} ]).
  [bork,bork,bork]
 
  2> sc:key_duplicate([ {3,sunday}, {2,monster}, {2,truck}, {1,'MADNESS'} ]).
  [sunday,sunday,sunday,monster,monster,truck,truck,'MADNESS']

Introduced in: Version 462

key_extrema/1

Equivalent to key_extrema(1, List).

Untested Stoch untested

Introduced in: Version 606

key_extrema/2

Untested Stoch untested

Introduced in: Version 601

key_group/2

Untested Stoch untested

Introduced in: Version 538

key_group/3

Untested Stoch untested

Introduced in: Version 538

key_max/1

Equivalent to key_max(1, List).

Untested Stoch untested

Introduced in: Version 605

key_max/2

Untested Stoch untested

Introduced in: Version 604

key_min/1

Equivalent to key_min(1, List).

Untested Stoch untested

Introduced in: Version 607

key_min/2

Untested Stoch untested

Introduced in: Version 607

kurtosis/1

Equivalent to central_moment(List, 4).

BUGGY Untested Stoch untested

Introduced in: Version 494

labelled_fk_readability/1

Untested Stoch untested Provides mandated human-readable labels for Flesch-Kincaid readability calculations. @see http://en.wikipedia.org/wiki/Flesch-Kincaid_Readability_Test and http://www.readabilityformulas.com/graphics/fleschresults.gif .

Introduced in: Version 707

last_while_pos/2

Untested Stoch untested Returns the last element of the initial sequence where all items pass the predicate function.

  1> sc_lists:last_while_pos(fun erlang:is_atom/1, [a,b,c,d,2,f]).
  4
 
  2> sc_lists:last_while_pos(fun erlang:is_atom/1, [a,b,c,d,r,f]).
  6
 
  3> sc_lists:last_while_pos(fun erlang:is_atom/1, [1,a,b,c,d,r,f]).
  false

Introduced in: Version 538

last_while_pos/3

Untested Stoch untested

levenshtein/2

Untested Stoch untested, by fredrik svensson and adam lindberg, from http://www.merriampark.com/lderlang.htm

Introduced in: Version 626

list_intersection/2

Equivalent to list_intersection(List1, List2, unsorted).

list_intersection/3

Stoch untested Efficiently computes the intersection of two lists. The third parameter, which is optional and defaults to unsorted, is either the atom sorted or unsorted. If sorted is used, the function will sort both inputs before proceeding, as it requires sorted lists; as such, if you already know your lists to be sorted, passing unsorted will save some time. The return list will be reverse sorted.

  1> sc:list_intersection([1,2,3,4,5,2,3,10,15,25,30,40,45,55],[1,3,5,5,5,15,20,30,35,40,50,55]).
  [55,40,30,15,5,3,1]
 
  2> sc:list_intersection([1],[2]).
  []

Introduced in: Version 471

list_product/1

Stoch untested Takes the product of all numbers in the list. Offered mostly to make dependant code clearer.

  1> sc:list_product([1,2,5.4]).
  10.8

Introduced in: Version 476

list_to_number/1

Untested Stoch untested Converts a list into a number; integers will be returned if there is no mantissa in the list representation.

  1> sc:list_to_number("2").
  2
 
  2> sc:list_to_number("2.0").
  2.0
 
  3> sc:list_to_number("2.1").
  2.1

Introduced in: Version 574

list_to_term/1

Untested Stoch untested Like binary_to_term, but not so much for binaries. Thanks, dizzyd (modified for error reporting)

Introduced in: Version 568

map_scanline/2

Untested Stoch untested Parses a string on all three newline types, discarding any empty lines; applies F as a functor to each line, and returns the tuple of the remainder and then a list of all results from the functor(s) issued

Introduced in: Version 626

map_scanline/3

Untested Stoch untested Third argument passes argument list as secondary argument to the functor; useful for passing ancillary state

Introduced in: Version 626

markhov_chain/2

Generates a markhov chain from a list of lists.

Introduced in: Version 703

median/1

Untested Stoch untested Takes the median (central) value of a list. Sorts the input list, then finds and returns the middle value.

  1> sc:median([1,2,999]).
  2

Introduced in: Version 488

See also: arithmetic_mean/1, mode/1.

median_absolute_deviation/1

Untested Stoch untested Calculate the median absolute deviation of a numericlist().

  1> sc:median_absolute_deviation([1,1,2,2,4,6,9]).
  1

Introduced in: Version 501

member_sets/1

Equivalent to member_sets(Memberships, no_absence).

member_sets/2

Stoch untested For a list of memberships, return every possible combination of one representative member from each list. The parameter AllowAbsence controls whether memberships may be unrepresented; if unrepresented memberships are possible, then one possible representation becomes the empty list.

  1> sc:member_sets([ [a,b],[1,2,3],[i,ii,iii] ], no_absence).
  [ [a,1,i], [a,1,ii], [a,1,iii], [a,2,i], [a,2,ii], [a,2,iii], [a,3,i], [a,3,ii], [a,3,iii],
    [b,1,i], [b,1,ii], [b,1,iii], [b,2,i], [b,2,ii], [b,2,iii], [b,3,i], [b,3,ii], [b,3,iii]]
 
  2> sc:member_sets([ [a,b],[1,2],[i,ii] ], allow_absence).
  [ [], [i], [ii], [1], [1,i], [1,ii], [2], [2,i], [2,ii], [a], [a,i], [a,ii], [a,1], [a,1,i],
    [a,1,ii], [a,2], [a,2,i], [a,2,ii], [b], [b,i], [b,ii], [b,1], [b,1,i], [b,1,ii], [b,2],
    [b,2,i], [b,2,ii] ]
 
  3> sc:member_sets([ [toast,pancakes], [sausage,bacon] ] ).
  [[toast,sausage],
   [toast,bacon],
   [pancakes,sausage],
   [pancakes,bacon]]
 
  4> sc:member_sets([ [toast,pancakes], [sausage,bacon] ], no_absence ).
  [[toast,sausage],
   [toast,bacon],
   [pancakes,sausage],
   [pancakes,bacon]]
 
  5> sc:member_sets([ [toast,pancakes], [sausage,bacon] ], allow_absence).
   [[],
   [sausage],
   [bacon],
   [toast],
   [toast,sausage],
   [toast,bacon],
   [pancakes],
   [pancakes,sausage],
   [pancakes,bacon]]
 
  6> Format = fun(Person, Place, Weapon) -> "It was " ++ Person ++ " in the " ++ Place ++ " with the " ++ Weapon ++ "!" end.
  #Fun<erl_eval.18.105910772>
 
  7> [ Format(Pe,Pl,WW) || [Pe,Pl,WW] <- sc:member_sets( [ ["Col. Mustard", "Ms. Scarlett"], ["conservatory", "hallway", "kitchen"], ["lead pipe"] ] ) ].
  ["It was Col. Mustard in the conservatory with the lead pipe!",
   "It was Col. Mustard in the hallway with the lead pipe!",
   "It was Col. Mustard in the kitchen with the lead pipe!",
   "It was Ms. Scarlett in the conservatory with the lead pipe!",
   "It was Ms. Scarlett in the hallway with the lead pipe!",
   "It was Ms. Scarlett in the kitchen with the lead pipe!"]

Introduced in: Version 466

merge_settings/2

Introduced in: Version 576

mersenne_prime/1

Untested Stoch untested

Introduced in: Version 512

mod/2

Untested Stoch untested Takes the modulus of an integer by another integer. Luckily, erlang calls what most languages refer to as modulus by its correct name, remainder (c's %, erlang's rem). Modulus is implemented incorrectly in nearly every language, because chip vendors implement remainder and the wrong name stuck. The difference is in how the operator reacts to a negative Base: -10 modulo 3 is 2, whereas -10 rem 3 is -1. Remainder takes the residue of dividing the base by the lowest (nearest negative infinity) integer N adjacent the real valued divisor; modulo returns the highest, which is less CPU efficient but always provides an answer on [0..Range-1].

  1> sc:mod(10,3).
  1
 
  2> [ sc:mod(X,4) || X <- lists:seq(-10,10) ].
  [2,3,0,1,2,3,0,1,2,3,0,1,2,3,0,1,2,3,0,1,2]

Introduced in: Version 507

mode/1

Untested Stoch untested Takes the mode (most common) value(s) of a list, as a list. If there are more than one value tied for most common, all tied will be returned. This function is safe for mixed-type lists, and does not perform deep traversal (that is, the mode of [ [2,2] ] is [2,2], not 2).

  sc:mode([1,2,1,3,1,4]).
  [1]
 
  2> sc:mode([ [1,2,3], [2,3,4], [3,4,5], [2,3,4] ]).
  [[2,3,4]]
 
  3> sc:mode([ a,b, 1, a,b, 2, a,b, 3 ]).
  [a,b]

Introduced in: Version 497

See also: arithmetic_mean/1, median/1.

module_abstract_representation/1

Untested Stoch untested

Introduced in: Version 553

module_abstract_representation/2

Untested Stoch untested

Introduced in: Version 553

module_atoms/1

Untested Stoch untested

Introduced in: Version 533

module_attribute/1

Untested Stoch untested Look up all attributes of a given module.

  1> sc:module_attribute(sc).
  [{author,"John Haugeland <stonecypher@gmail.com>"},
   {bugtracker,"http://crunchyd.com/forum/project.php?projectid=7"},
   {currentsource,"http://crunchyd.com/release/scutil.zip"},
   {description,"StoneCypher's utility library."},
   {library_requirements,[{testerl,16}]},
   {license,[{mit_license,"http://scutil.com/license.html"}]},
   {publicforum,"http://crunchyd.com/forum/scutil-discussion/"},
   {publicsvn,"svn://crunchyd.com/scutil/"},
   {svn_head,"$HeadURL$"},
   {svn_id,"$Id$"},
   {svn_revision,"$Revision$"},
   {testerl_export,[{[],scutil_testsuite}]},
   {vsn,[134633400955530778836494569152232539093]},
   {webpage,"http://scutil.com/"}]

Introduced in: Version 520

module_attribute/2

BUGGY Untested Stoch untested Look up an Erlang module attribute value by title. Originally found at Mastering Erlang Part 3; subsequently cleaned up and given error reporting.

  1> sc:module_attribute(scutil, author).
  "John Haugeland <stonecypher@gmail.com>"
 
  2> sc:module_attribute(scutil, license).
  [{mit_license,"http://scutil.com/license.html"}]

Thanks to Alain O'Dea for pointing out defects in this routine regarding repeated module elements, and available improvements to the provided API. Mr. O'Dea's insightful advice will be implemented, but that time has not yet come.

Introduced in: Version 520

module_feature/2

Untested Stoch untested

Introduced in: Version 521

module_is_loaded/1

Untested Stoch untested

Introduced in: Version 666

moment/2

Untested Stoch untested Takes the Nth moment of a list. The Nth moment of a list is the arithmetic mean of the list items, each taken to the Nth power. Fractional Ns are well defined and have obscure uses, though most will only ever use this with integer values of N; this function is valid for both. Not to be confused with central_moment/2. Thanks to Kraln and Chile for straightening me out on moments and central moments.

  1> sc:moment([1,1,1], 2).
  1.0
 
  2> sc:moment([2,2,2], 2).
  4.0
 
  3> sc:moment([1,2,3], 2).
  4.666666666666667
 
  4> sc:moment([1,2,3], 3).
  12.0
 
  5> sc:moment([1,2,3], 3.5).
  19.693026767781483

Introduced in: Version 491

moments/1

Equivalent to [moment(List, N) || N <- [2, 3, 4]].

Untested Stoch untested

Introduced in: Version 491

moments/2

Equivalent to [moment(List, N) || N <- Moments].

Untested Stoch untested

Introduced in: Version 491

months_as_short_atoms/0

Introduced in: Version 665

multi_deck/2

Incomplete Untested Stoch untested Makes a number of instances of a deck, and applies a different back to each. The first parameter may be a positive_integer(), at which point the color sequence from standard_backs/0 will be used; otherwise, a list may be used, which will be used as the card backs (there is no requirement regarding their type or uniqueness, only that they be presented as a list.) The second parameter may be a function(), which will be called to generate a list of cards, or a list of cards which will be used directly.

Introduced in: Version 729

multi_do/3

Equivalent to multi_do(C, M, F, []).

Introduced in: Version 620

multi_do/4

Untested Stoch untested Take an iteration count, a module name, a function name and an argument list, and repeatedly apply the argument list to the module/function, count times. This is primarily useful with nondeterministic functions whose result might change despite identical arguments, such as functions with random behavior; for example, this function is invoked to implement stochastic testing in TestErl.

  1> sc:multi_do(10, scutil, rand, [100]).
  [9,94,4,82,77,44,89,19,45,92]
 
  2> sc:multi_do(10, scutil, rand, [10000]).
  [2377,2559,1713,8489,4468,3261,3344,3751,380,2525]

Introduced in: Version 620

naive_bayes_likelihood/4

Equivalent to naive_bayes_likelihood(FeatureEvident, FeatureTotal, NonFeatureEvident, NonFeatureTotal, simple).

Introduced in: Version 772

naive_bayes_likelihood/5

Stoch untested Calculates the contributing difference probability, feature likelihood and non-feature likelihood of an event via Naive Bayes Likelihood.

  1> sc:naive_bayes_likelihood(48, 60, 4, 40).
  0.9230769230769231
 
  2> sc:naive_bayes_likelihood(48, 60, 4, 40, full).
  [ {contributing_difference,0.7000000000000001},
    {likelihood_featured,0.8},
    {likelihood_nonfeatured,0.1},
    {evident_feature_likelihood,0.9230769230769231} ]
 
  3> sc:naive_bayes_likelihood(48, 60, 4, 40, simple).
  0.9230769230769231

Introduced in: Version 772

nearest_to/2

Untested Stoch untested

Introduced in: Version 517

neighbors/2

Introduced in: Version 683

ngrams/1

Introduced in: Version 652

ngrams/2

Introduced in: Version 652

notebook_contains/2

Introduced in: Version 752

notebook_contents/1

Introduced in: Version 757

notebook_create/1

Introduced in: Version 747

notebook_destroy/1

Introduced in: Version 748

notebook_read/2

Introduced in: Version 751

notebook_remove/2

Removes an item from a notebook. Like most other notebook functions, if the referred notebook does not already exist, it will be created. notebook_write/3 for details.

  1> sc:notebook_write("Test", "test", "test").
  ok
 
  2> sc:notebook_read("Test", "test").
  {value,"test"}
 
  3> sc:notebook_remove("Test", "test").
  ok
 
  4> sc:notebook_read("Test", "test").
  undefined
 
  5> sc:notebook_read("Not an existing notebook", "test").
  ok

Introduced in: Version 753

notebook_validate/1

Introduced in: Version 749

notebook_write/3

Introduced in: Version 750

now_str_utc24/0

Introduced in: Version 744

nth_difference/2

Untested Stoch untested

Introduced in: Version 547

null_postpad_bin_to/2

Introduced in: Version 644

nybble_to_hex/1

Convert a nybble() to a hexchar().

  1> sc:nybble_to_hex(7).
  55
 
  2> sc:nybble_to_hex(15).
  102

Introduced in: Version 570

out_of_range/3

Introduced in: Version 650

paper_3d_basic_depth/4

Untested Stoch untested

Introduced in: Version 633

paper_3d_render/1

Untested Stoch untested

Introduced in: Version 634

paper_3d_render/2

Untested Stoch untested

Introduced in: Version 634

paper_3d_render/3

Untested Stoch untested

Introduced in: Version 634

paper_3d_render/4

Untested Stoch untested

Introduced in: Version 634

parity/1

Equivalent to even_or_odd(Num).

Documentary convenience function (synonymous with even_or_odd/1) that returns the atoms even or odd for any integer.

  1> sc:parity(3).
  odd

Introduced in: Version 648

partition_by_residue/2

Untested Stoch untested

Introduced in: Version 537

pearson_correlation/1

Untested Stoch untested Compute the Pearson Correlation Coefficient of a list of coordinate tuples.

  1> sc_correlate:pearson([ {1,1}, {2,2}, {3,3}, {4,4}, {5,5} ]).
  {r,1.0}
 
  2> sc_correlate:pearson([ {1,5}, {2,4}, {3,3}, {4,2}, {5,1} ]).
  {r,-1.0}
 
  3> sc_correlate:pearson([ {1,3}, {2,3}, {3,3}, {4,3}, {5,3} ]).
  {r,0.0}
 
  4> sc_correlate:pearson([ {1,2}, {2,2.5}, {3,3}, {4,3.5}, {5,4} ]).
  {r,1.0}
 
  5> sc_correlate:pearson([ {1,2}, {2,2.4}, {3,3}, {4,3.6}, {5,4} ]).
  {r,0.9970544855015818}

Introduced in: Version 559

pearson_correlation/2

Equivalent to pearson(lists:zip(List1, List2)).

permute/1

Equivalent to permute(List, length(List)).

permute/2

Stoch untested Calculate either the full or the depth-limited permutations of a list, order sensitive; contrast combinations/2. Permutations are all valid orderings of a set of tokens; the permutations of [a,b] for example are [a,b] and [b,a]. Depth limitation means the permutations of a smaller count of tokens from the main set; the 2-limited permutations of [a,b,c] for example are [a,b], [a,c], [b,a], [b,c], [c,a] and [c,b]. Permutations are not ordered. Mixed-type lists are safe; items are shallow evaluated, meaning that sublists within the list are treated as single elements, and will neither be rearranged nor will have elements selected from within them.

  1> sc:permute(["dave","kate","pat"]).
  [ { "pat",  "kate", "dave" },
    { "kate", "pat",  "dave" },
    { "pat",  "dave", "kate" },
    { "dave", "pat",  "kate" },
    { "kate", "dave", "pat"  },
    { "dave", "kate", "pat"  } ]
 
  2> sc:permute([fast, strong, smart, lucky], 2).
  [ { strong, fast   },
    { smart,  fast   },
    { lucky,  fast   },
    { fast,   strong },
    { smart,  strong },
    { lucky,  strong },
    { fast,   smart  },
    { strong, smart  },
    { lucky,  smart  },
    { fast,   lucky  },
    { strong, lucky  },
    { smart,  lucky  } ]

Introduced in: Version 474

power_set/1

Untested Stoch untested

Introduced in: Version 589

probability_all/1

Untested Stoch untested Calculates the likelihood that all items in a list of probabilities expressed on the real interval will occur.

  1> sc:probability_all([ 0.5, 0.4, 0.3 ]).
  0.06
  2> sc:probability_all([ 0.5, 0.5, 0.5 ]).
  0.125
  3> sc:probability_all([ 0.9, 0.9, 0.9, 0.9, 0.9 ]).
  0.5904900000000002

Notice the accumulated float rounding error.

  4> sc:probability_all([ 0.8, 0.8, 0.8, 0.8, 0.8, 0.8 ]).
  0.2621440000000001

That's right, six 0.8s is 1 in 4. Do the math.

Introduced in: Version 651

probability_any/1

Incomplete Todo Comeback Untested Stoch untested

Introduced in: Version 652

qsp_average/2

Incomplete Untested Stoch untested Takes the quadratic scalar product average of a vector W and a list of vectors X. The QSP Average is the arithmetic mean of the result set Y, where Y is generated as the square of the magnitude of the dot product of W and each individual vector in X. @see http://www.inf.fu-berlin.de/inst/ag-ki/rojas_home/documents/1996/NeuralNetworks/K5.pdf pdf-page 15.

  1> sc:qsp_average([1,2,3], [[0,0,0],[0,0,0]]).
  0.0
 
  2> sc:qsp_average([1,2,3], [[0,0,1],[0,0,0]]).
  4.5
 
  3> sc:qsp_average([1,2,3], [[0,1,0],[0,0,0]]).
  2.0
 
  4> sc:qsp_average([1,2,3], [[1,0,0],[0,0,0]]).
  0.5
 
  5> sc:qsp_average([1,2,3], [[1,1,1],[0,0,0]]).
  18.0
 
  6> sc:qsp_average([1,2,3], [[0,0,0],[1,1,1]]).
  18.0
 
  7> sc:qsp_average([1,2,3], [[1,1,1],[1,1,1]]).
  36.0

Introduced in: Version 726

rand/1

Untested Stoch untested Returns a pseudorandom integer on the range [0 - (Range-1)] inclusive.

  1> sc:rand(100).
  9
 
  2> [ sc:rand(100) || X <- lists:seq(1,10) ].
  [12,27,99,86,20,96,28,36,28,15]
 
  3> sc:histograph([ sc:rand(10) || X <- lists:seq(1,10000) ]).
  [{0,992}, {1,990}, {2,992}, {3,1033}, {4,1017}, {5,1003}, {6,996}, {7,1024}, {8,969}, {9,984}]
 
  4> sc:histograph([ sc:rand(10) || X <- lists:seq(1,10000) ]).
  [{0,1028}, {1,979}, {2,934}, {3,970}, {4,1035}, {5,1007}, {6,986}, {7,1012}, {8,1052}, {9,997}]

Introduced in: Version 595

random_from/1

Equivalent to from(1, List, no_remainder).

Introduced in: Version 593

random_from/2

Equivalent to from(N, List, no_remainder).

Introduced in: Version 593

random_from/3

Untested Stoch untested Take N non-repeating random elements from a list in undefined order. If the atom remainder is passed in as the third argument, the unused portion of the source list will be returned as the second member of a 2ary tuple with the results; the default is no_remainder, which only returns the result set. Mixed type input lists are perfectly safe, and membership for random selection is shallow (ie, [ [1,2], [3,4] ] as an input list would only generate outputs of lists, never integers.)

  1> sc:random_from([monday,tuesday,wednesday,thursday,friday]).
  friday
 
  2> sc:random_from(4, lists:seq(1,20)).
  [6,3,15,12]
 
  3> sc:random_from(3, [warrior, mage, cleric, thief, paladin, ranger, bard]).
  [cleric,warrior,ranger]
 
  4> sc:random_from(6, [mixed, [1,2,3], 4, {five,5}, 3, 67.2, <<"Hello">>, 8]).
  [[1,2,3],{five,5},4,mixed,<<"Hello">>,67.2]
 
  5> {Team1, Team2} = sc:random_from(3, [alice,bob,cathy,dave,edward,fawn], remainder).
  {[cathy,fawn,dave],[bob,edward,alice]}
 
  6> Team1.
  [cathy,fawn,dave]
 
  7> Where_Food = fun() -> sc:random_from([deli, fastfood, chinese, mexican, steakhouse, bistro, greek, indian, thai, sushi]) end.
  #Fun<erl_eval.20.67289768>
 
  8> Where_Food().
  thai

Introduced in: Version 593

random_from_weighted/1

Untested Stoch untested Take a random single item from a list with weighted probabilities. Probabilities may be any numeric type, and may be any non-negative value (items with zero probability will be omitted). Input is a weightlist(), which is a list in the form [{Item,Probability}, {I2,P2}, ...]. There is no requirement to normalize probabilities to any range, though probabilities normalized to ranges will still work as expected.

  1> sc:from([ {quad,4}, {double,2}, {single,1} ]).
  quad
 
  2> [ sc:from_weighted([ {quad,4}, {double,2}, {single,1} ]) || X <- lists:seq(1,10) ].
  [single,quad,quad,double,quad,double,quad,quad,quad,double]
 
  3> sc:histograph([ sc:from_weighted([ {quad,4}, {double,2}, {single,1} ]) || X <- lists:seq(1,777777) ]).
  [{double,222200},{quad,444165},{single,111412}]

Introduced in: Version 592

random_unicode_char/0

Introduced in: Version 660

range_scale/1

Stoch untested Get the scale of a same-sign numeric range. Gives nonsense results for non-numeric lists, or for lists which have both positive and negative members. For a numeric list [4,5,6,12], the scale of the range 4..12 is 3:1, which is represented as 3.0 .

  1> sc:range_scale([3, 4, 5, 6]).
  2.0
 
  2> sc:range_scale([3, 6]).
  2.0
 
  3> sc:range_scale([6, 5, 3]).
  2.0
 
  4> sc:range_scale([3, 4, 5, 6, 7, 7.5]).
  2.5
 
  5> sc:range_scale([3, 10, 12, 99]).
  33.0
 
  6> sc:range_scale([3, 3, 3]).
  1.0

Introduced in: Version 479

receive_one/0

Untested Stoch untested Pop the front of the message queue and return it as {item,X}, or return nothing_there for empty queues; do not block.

  1> sc:receive_one().
  nothing_there
 
  2> self() ! message.
  message
 
  3> sc:receive_one().
  {item,message}
 
  4> sc:receive_one().
  nothing_there

Introduced in: Version 582

record_member/2

Untested Stoch untested TODO: Needs Example Checks whether E is a member element of record R, analogous to lists::member(E, L). This function does not have examples because the shell does not correctly handle records; todo: add examples later

Introduced in: Version 616

replace/3

reset_counter/1

Equivalent to set_counter_value(Name, 0).

Untested Stoch untested Resets a counter's value to zero.

  1> sc:counter_at(hello).
  0
 
  2> sc:set_counter_value(hello,4).
  4
 
  3> sc:counter_at(hello).
  4
 
  4> sc:reset_counter(hello).
  0
 
  5> sc:counter_at(hello).
  0

Introduced in: Version 679

reverse_filter/2

Untested Stoch untested

Introduced in: Version 545

reverse_map/2

Untested Stoch untested

Introduced in: Version 546

reverse_map_filter/3

Untested Stoch untested

Introduced in: Version 544

root_mean_square/1

Untested Stoch untested Calculates the root mean square of the values in the list.

  1> sc:root_mean_square([1,2,3,4,5]).
  3.3166247903554
 
  2> sc:root_mean_square([2,2,2]).
  2.0

Introduced in: Version 505

root_sum_square/1

Untested Stoch untested Calculate the magnitude (also known as the root sum square) of a vector.

Introduced in: Version 506

rotate_list/2

Tested Rotates the front Distance elements of a list to the back, in order. Negative distances rotate the back towards the front. Distances over the length of the list wrap in modulus.

  1> sc:rotate_list(2, [1,2,3,4,5,6,7,8]).
  [3,4,5,6,7,8,1,2]
 
  2> sc:rotate_list(-2, [1,2,3,4,5,6,7,8]).
  [7,8,1,2,3,4,5,6]
 
  3> sc:rotate_list(0, [1,2,3,4,5,6,7,8]).
  [1,2,3,4,5,6,7,8]
 
  4> sc:rotate_list(16, [1,2,3,4,5,6,7,8]).
  [1,2,3,4,5,6,7,8]

Introduced in: Version 463

rotate_to_first/2

Stoch untested Rotates the list to the first instance of Item.

  1> sc:rotate_to_first(c, [a,b,c,d,e]).
  [c,d,e,a,b]
 
  2> sc:rotate_to_first(j, [a,b,c,d,e]).
  no_such_element

Introduced in: Version 464

rotate_to_last/2

Stoch untested Rotates the list so that the first instance of Item becomes the last element in the list.

  1> sc:rotate_to_last(c, [a,b,c,d,e]).
  [d,e,a,b,c]
 
  2> sc:rotate_list(j, [a,b,c,d,e]).
  no_such_element

Introduced in: Version 464

sanitize_filename/1

Untested Stoch untested Sanitize an arbitrary string to be appropriate for Windows and Unix filesystems, and URLs.

  1> sc:sanitize_filename("\h/e~l%lo! w^o@r#l*d.").
  "helloworld"

Introduced in: Version 628

See also: sanitize_tokens/2.

sanitize_tokens/2

Stoch untested Remove unacceptable elements from an input list, as defined by another list or a filter function. Common reasons for sanitization include reducing arbitrary or bulk data to key format (such as using an original filename and new size to generate a new filename or database key) and removing malformed items from a list before processing.

  1> sc:sanitize_tokens("ae0z4nb'wc-04bn ze0e 0;4ci ;e0o5rn;", "ace").
  "aeceece"
 
  2> Classifier = fun(apple) -> true; (banana) -> true; (cherry) -> true; (date) -> true; (elderberry) -> true; (_) -> false end.
  #Fun<erl_eval.6.13229925>
 
  3> sc:sanitize_tokens([apple, boat, cherry, dog, elderberry], Classifier).
  [apple,cherry,elderberry]
 
  4> Vowels = fun($a)->true; ($e)->true; ($i)->true; ($o)->true; ($u)->true; ($A)->true; ($E)->true; ($I)->true; ($O)->true; ($U)->true; (_)->false end.
  #Fun<erl_eval.6.13229925>
 
  5> sc:sanitize_tokens("A quick brown fox jumped over the lazy dog", Vowels).
  "Auiooueoeeao"
 
  6> sc:sanitize_tokens("A quick brown fox jumped over the lazy dog", "abcdefABCDEF").
  "Acbfedeead"
 
  7> BobcatGoldthwait = fun(X) -> sc:sanitize_tokens(X, "aeiouAEIOU") end.
  #Fun<erl_eval.6.13229925>
 
  8> BobcatGoldthwait("A quick brown fox jumped over the lazy dog").
  "Auiooueoeeao"

Introduced in: Version 477

See also: sanitize_filename/1.

second_difference/1

Untested Stoch untested

Introduced in: Version 547

send_receive/2

Untested Stoch untested (Blocking) First send a message to an entity. Then pop the front of the message queue and return it as {item,X}; block.

  1> sc:send_receive(self(), message).
  {item,message}

Introduced in: Version 578

send_receive/3

Untested Stoch untested (Non-Blocking) First send a message to an entity. Then pop the front of the message queue and return it as {item,X}, or return nothing_there for empty queues; do not block.

  1> sc:send_receive(self(), message).
  {item,message}

Introduced in: Version 579

send_receive_masked/3

Untested Stoch untested (Blocking) First send a message to an entity. Then pop the first message queue item matching the mask as a 2-tuple, and return it as {Mask,X}; block.

  1> sc:send_receive(self(), message).
  {item,message}

Introduced in: Version 580

send_receive_masked/4

Untested Stoch untested (Non-Blocking) First send a message to an entity. Then pop the front of the message queue and return it as {Mask,X}, or return nothing_there for empty queues; do not block.

  1> sc:send_receive(self(), message).
  {item,message}

Introduced in: Version 581

set_counter_value/2

Untested Stoch untested Sets a counter's value to a specific value.

  1> sc:counter_at(hello).
  0
 
  2> sc:set_counter_value(hello,4).
  4
 
  3> sc:counter_at(hello).
  4
 
  4> sc:reset_counter(hello).
  0
 
  5> sc:counter_at(hello).
  0

Introduced in: Version 678

shared_keys/1

Stoch untested Create sorted list X of 3-ary tuples {K,Ai,Bi} from sorted lists A, B of 2ary {K,Ai}/{K,Bi} tuples, where key K appears in both A and B.

  1> sc:shared_keys([{1,a},{2,a},{3,a}],[{1,b},{3,b},{4,b}]).
  [{1,a,b},{3,a,b}]
 
  2>sc:shared_keys([{1,a},{2,a}],[{3,b},{4,b}]).
  []

Introduced in: Version 475

shared_keys/2

Equivalent to shared_keys(lists:zip(lists:sort(A), lists:sort(B))).

Stoch untested Equivalent to shared_keys/1, but skips sorting the lists (and thus requires pre-sorted lists), which may save significant work repetition.

shared_keys/3

Equivalent to shared_keys(lists:sort(A), lists:sort(B)).

Stoch untested Equivalent to shared_keys/2, but skips sorting the lists (and thus requires pre-sorted lists), which may save significant work repetition.

show/1

Untested Stoch untested

Introduced in: Version 637

shuffle/1

Untested Stoch untested Return a list with the original list's shallow members in a random order. Deep lists are not shuffled; [ [a,b,c], [d,e,f], [g,h,i] ] will never produce sublist reorderings ([b,c,a]) or list mixing ([b,g,e]), only reordering of the three top level lists. The output list will always be the same length as the input list. Repeated items and mixed types in input lists are safe.

  1> sc:shuffle(lists:seq(1,9)).
  [8,4,7,9,5,2,6,1,3]
 
  2> {TheFaces, TheSuits} = {  [ace] ++ lists:seq(2,10) ++ [jack,queen,king],  [hearts,spades,clubs,diamonds]  }
  {[ace,jack,queen,king,2,3,4,5,6,7,8,9,10],
   [hearts,spades,clubs,diamonds]}
 
  3> Deck = sc:shuffle([ {Face,Suit} || Face <- TheFaces, Suit <- TheSuits ]).
  [ {6,spades}, {7,hearts}, {8,clubs}, {queen,spades}, {6,diamonds}, {ace,...}, {...} | ...]
 
  4> sc:shuffle([ duck,duck,duck,duck, goose ]).
  [duck,goose,duck,duck,duck]

Introduced in: Version 590

simple_ranking/1

Untested Stoch untested Returns a ranked ordering of the list without tie rankings.

  1> sc_rank:simple([10,90,20,80,30,70,40,60,50]).
  [{1,90}, {2,80}, {3,70}, {4,60}, {5,50}, {6,40}, {7,30}, {8,20}, {9,10}]
 
  2> sc_rank:simple([10,10,10,10]).
  [{1,10},{2,10},{3,10},{4,10}]

Introduced in: Version 560

skewness/1

Equivalent to central_moment(List, 3).

Untested Stoch untested

Introduced in: Version 493

spearman_correlation/1

Untested Stoch untested Compute the Spearman's Rank Correlation Coefficient of a list of coordinate tuples.

  1> sc:spearman([ {1,1}, {2,2}, {3,3}, {4,4}, {5,5} ]).
  {rsquared,1.0}
 
  2> sc:spearman([ {1,5}, {2,4}, {3,3}, {4,2}, {5,1} ]).
  {rsquared,-1.0}
 
  3> sc:spearman([ {1,3}, {2,3}, {3,3}, {4,3}, {5,3} ]).
  {rsquared,0.5}
 
  4> sc:spearman([ {1,2}, {2,2.5}, {3,3}, {4,3.5}, {5,4} ]).
  {rsquared,1.0}
 
  5> sc:spearman([ {1,2}, {2,2.4}, {3,3}, {4,3.6}, {5,4} ]).
  {rsquared,1.0}

Introduced in: Version 558

spearman_correlation/2

Equivalent to spearman_correlation(lists:zip(List1, List2)).

split_at/2

Untested Stoch untested

Introduced in: Version 541 TODO

square/1

Untested Stoch untested Squares the input; convenient in list comprehensions to prevent recalculation, and clear in the fashion of documentary functions.

  1> sc:square(2).
  4
 
  2> sc:square(2.5).
  6.25

Introduced in: Version 508

srand/0

Untested Stoch untested (Called automatically) Instantiates the random source, destroying a prior source if needed, and seeds the source with the clock, returning the seed used. Generally speaking, you do not need this function; this is used manually when you want to know what seed was used, for purposes of recreating identical pseudorandom sequences. Otherwise, rand() will call this once on its own. Because the scutil random system spawns a utility process to maintain random state, this function should be considered to have side effects for purposes of testing. (Indeed, in a sense, this function's entire purpose is to cause a side effect.)

  1> sc:srand().
  {ok,{seeded,{1227,902172,685000}}}
 
  2> sc:srand().
  {ok,{seeded,{1227,902173,231000}}}

Introduced in: Version 598

srand/3

Untested Stoch untested (Called automatically) Instantiates the random source, destroying a prior source if needed, and seeds the source with the three integer seed you provide, returning the seed used. Generally speaking, you do not need this function; this is used manually when you want set what seed is used, for purposes of recreating identical pseudorandom sequences. Otherwise, rand() will call this once on its own. Because the scutil random system spawns a utility process to maintain random state, this function should be considered to have side effects for purposes of testing. (Indeed, in a sense, this function's entire purpose is to cause a side effect.)

  1> sc:srand(1,2,3).
  {ok,{seeded,{1,2,3}}}
 
  2> sc:srand().
  {ok,{seeded,{1227,902568,604600}}}
 
  3> sc:srand(1,2,3).
  {ok,{seeded,{1,2,3}}}

Introduced in: Version 598

standard_card_backs/0

Incomplete Untested Stoch untested Returns the list of colors which are used, in order, as the standard back colors of a series of decks for multi_deck/2. Each color is presented as an atom.

  1> sc:standard_card_backs().
  [ red, blue, green, black, purple, orange, brown, yellow,
    teal, gray, cyan, indigo, pink, white, tan, maroon,
    navy, forest, leaf, sky, brick ]
 
  2> length(sc:standard_card_backs()).
  24

Introduced in: Version 728

standard_card_backs/1

Incomplete Untested Stoch untested Returns the front of the list of colors which are used, in order, as the standard back colors of a series of decks for multi_deck/2. Each color is presented as an atom. If you request more colors than are in the list, the list [1,2...Count] is provided instead.

  1> sc:standard_card_backs(5).
  [ red, blue, green, black, purple ]
 
  2> sc:standard_card_backs(29).
  [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]

Introduced in: Version 728

start_register_if_not_running/2

Untested Stoch untested

Introduced in: Version 635

start_register_if_not_running/3

Equivalent to start_register_if_not_running(node(), Name, Module, Function, []).

Untested Stoch untested

Introduced in: Version 618

start_register_if_not_running/4

Equivalent to start_register_if_not_running(node(), Name, Module, Function, Args).

Untested Stoch untested

start_register_if_not_running/5

Untested Stoch untested Check whether a process is registered locally, and if not, spawn it with a give function and arguments.

  1> whereis(test).
  undefined
 
  2> sc:start_register_if_not_running(node(), test, scutil, wait_until_terminate, []).
  { ok, <0.726.0> }
 
  3> whereis(test).
  <0.726.0>
 
  4> test ! terminate.
  terminate
 
  5> whereis(test).
  undefined
 
  6> sc:start_register_if_not_running(node(), test, scutil, wait_until_terminate, []).
  { ok, <0.731.0> }
 
  7> whereis(test).
  <0.731.0>
 
  8> sc:start_register_if_not_running(node(), test, scutil, wait_until_terminate, []).
  { ok, <0.731.0> }
 
  9> whereis(test).
  <0.731.0>

Introduced in: Version 618

starts_with/2

Untested Stoch untested

Introduced in: Version 624

stretch_hash/3

Untested Stoch untested Stretches a hash with a list of salts. Some people incorrect refer to this as key strentghening. The process is a simple key-derivation function: repeat the application of a hash with a different pre-pend salt each time.

  1> Res = sc:stretch_hash("abc", fun erlang:md5/1, ["def", "ghi", "jkl", "mno"]).
  <<129,166,92,224,108,140,78,205,151,136,77,203,166,229,62,186>>
 
  2> sc:bin_to_hex_list(Res).
  "81a65ce06c8c4ecd97884dcba6e53eba"
 
  C:\projects\scutil\res>php
  <?php echo md5("mno" . md5("jkl" . md5("ghi" . md5("defabc", true), true), true)); ?>
  ^Z
  81a65ce06c8c4ecd97884dcba6e53eba

Introduced in: Version 641

svn_revision/1

Untested Stoch untested Scans a module for an attribute svn_revision, parses it in the format expected from the svn:keyword Revision, and returns the version number as an integer. To use, add a module attribute to your module as follows: -svn_revision("$+Revision$)., after removing the plus (if the plus wasn't there, the example would get corrupted when I updated the module ;)). Then set the svn keyword "Revision" on the file, and check it in. After that, your version is magically updated every time you check in! :D The sole argument to this function is the name of the module to be scanned, as an atom.

  1> sc:scan_svn_revision(testerl).
  16

Introduced in: Version 523

terminate_loop/0

Untested Stoch untested

Introduced in: Version 636

test/0

(not testworthy) Runs the test suite in terse form.

  1> sc:test().
    All 9 tests passed.
  ok

Introduced in: 458

test/1

(not testworthy) Runs the test suite in verbose form. Also responds to [verbose] to be more familiar to eunit devs. An (ancient) example of output:

  1> sc:test(verbose).
  ======================== EUnit ========================
  module 'sc'
    module 'sc_tests'
      Index of first tests
        sc_tests:73: index_of_first_test_ (0,  [ ])...ok
        sc_tests:74: index_of_first_test_ (b,  [ a,b,c ])...ok
        sc_tests:75: index_of_first_test_ (g,  [ a,b,c ])...ok
        [done in 0.046 s]
      Rotate list tests
        sc_tests:52: rotate_list_test_ (0,  [ ])...ok
        sc_tests:53: rotate_list_test_ (1,  [ ])...ok
        sc_tests:54: rotate_list_test_ (-1, [ ])...ok
        sc_tests:56: rotate_list_test_ (0,  [ a,b,c ])...ok
        sc_tests:57: rotate_list_test_ (1,  [ a,b,c ])...ok
        sc_tests:58: rotate_list_test_ (-1, [ a,b,c ])...ok
        sc_tests:59: rotate_list_test_ (3,  [ a,b,c ])...ok
        sc_tests:60: rotate_list_test_ (-3, [ a,b,c ])...ok
        sc_tests:61: rotate_list_test_ (9,  [ a,b,c ])...ok
        [done in 0.141 s]
      Key duplicate tests
        sc_tests:38: key_duplicate_test_ ([ ])...ok
        sc_tests:39: key_duplicate_test_ ([ {2,a} ])...ok
        sc_tests:40: key_duplicate_test_ ([ {2,a},{3,b} ])...ok
        [done in 0.047 s]
      Extrema tests
        sc_tests:19: extrema_test_ (1,2,3,4)...ok
        sc_tests:20: extrema_test_ (-1,-2,-3)...ok
        sc_tests:21: extrema_test_ (-1.1,0,1.1)...ok
        sc_tests:22: extrema_test_ (a,b,c)...ok
        sc_tests:23: extrema_test_ (1,a,{})...ok
        sc_tests:24: extrema_test_ (1)...ok
        sc_tests:26: extrema_test_ ([] error)...ok
        [done in 0.109 s]
      [done in 0.343 s]
    [done in 0.343 s]
  =======================================================
    All 22 tests passed.
  ok

Introduced in: 460

third_difference/1

Untested Stoch untested

Introduced in: Version 547

tied_ordered_ranking/1

Untested Stoch untested Returns a tied ranked ordering of the list, ordered according to the input ordering rather than the sorted ordering. As with tied/1, all rankings are floats, and ties are represented as the centers of ranges.

  1> sc:ordered([10,90,20,80,30,70,40,60,50]).
  [{9.0,10}, {1.0,90}, {8.0,20}, {2.0,80}, {7.0,30}, {3.0,70}, {6.0,40}, {4.0,60}, {5.0,50}]
 
  2> sc:ordered([100,200,200,300]).
  [{4.0,100},{2.5,200},{2.5,200},{1.0,300}]

Introduced in: Version 562

tied_ranking/1

Untested Stoch untested Returns a ranked ordering of the list with tie rankings. As such, for uniformity, all rankings are floats. Ties are represented as the centers of ranges.

  1> sc:tied([10,90,20,80,30,70,40,60,50]).
  [{1.0,90}, {2.0,80}, {3.0,70}, {4.0,60}, {5.0,50}, {6.0,40}, {7.0,30}, {8.0,20}, {9.0,10}]
 
  2> sc:tied([100,200,200,300]).
  [{1.0,300},{2.5,200},{2.5,200},{4.0,100}]

Introduced in: Version 561

time_diff/2

Returns the difference, in seconds as a float, between two erlang timestamps as returned by os:timestamp(). Negative differences are returned if the latter timestamp B is earlier than the former timestamp A. This is different than timer:now_diff/2 in that this works in floating point seconds, rather than integer microseconds. os:timestamp/0 should be used rather than erlang:now/0 because erlang:now/0 is massaged time - gaps are smoothed, reversals are prevented, reads are forced monotonic increasing, et cetera (thanks MononcQc,) whereas os:timestamp/0 is raw.

  1> A = os:timestamp().
  {1232,947675,340000}
 
  2> B = os:timestamp().
  {1232,947679,412000}
 
  3> sc:time_diff(A,B).
  4.072
 
  4> sc:time_diff(B,A).
  -4.072

Introduced in: Version 742

to_lines/1

Stoch untested Cuts a string according to any of the three newline conventions (even mixed), and discards empty strings. Mostly convenience and documentary.

  1> sc:to_lines("one\rtwo\nthree\r\nfour\r\r\rfive").
  ["one","two","three","four","five"]
 
  2> sc:to_lines("a\nb").
  ["a","b"]
 
  3> sc:to_lines("a\n\n\n\n\n\nb").
  ["a","b"]
 
  4> sc:to_lines("a\r\nb").
  ["a","b"]
 
  5> sc:to_lines("a\rb").
  ["a","b"]
 
  6> sc:to_lines("a\rb\nc\r\nd\n\r\r\ne")
  ["a","b","c","d","e"]
 
  7> sc:to_lines("").
  []
 
  8> sc:to_lines("\r\n\r\r\n\n\r").
  []

Introduced in: Version 705

to_list/1

Untested Stoch untested

Introduced in: Version 638

triangle_index/1

Untested Stoch untested

Introduced in: Version 632

triangle_index/2

Untested Stoch untested

Introduced in: Version 632

tuple_duplicate/2

Tested Creates a tuple of fixed width, repeating the given element the given number of times. This is equivalent to lists:duplicate.

  1> sc:tuple_duplicate(3,hi).
  {hi,hi,hi}
 
  2> sc:tuple_duplicate(0,hi).
  {}
 
  Unit, doc, spec and stochastic (correct length, is tuple, first item is correct) tested.

Introduced in: Version 809

tuple_member/2

Untested Stoch untested Checks whether E is a member element of tuple T, analogous to lists::member(E, L).

  1> sc:tuple_member(b, {a,b,c}).
  true
 
  2> sc:tuple_member(d, {a,b,c}).
  false
 
  3> sc:tuple_member([1,2], {[1,2]}).
  true

Introduced in: Version 615

tuple_sort/1

Untested Stoch untested

Introduced in: 610

tuple_sum/1

Untested Stoch untested Returns the sum of the numeric elements of a tuple, treating non-numeric elements as zero.

  1>

Introduced in: Version 609

type_of/1

Untested Stoch untested Fetch the type of the argument. Valid for any term. Fails before erlang 12, due to use of is_bitstring() .

  1> sc:type_of(1).
  integer
 
  2> sc:type_of({hello,world}).
  tuple

Introduced in: Version 722

unfunnel/2

Untested Stoch untested Reverse a marketing funnel, to go from goal needed to input needed.

  1> % Using the data from http://www.forentrepreneurs.com/lessons-from-leaders/jboss-example/
  1> sc:unfunnel(300, [{1/4,"Web activity scoring"}, {1/3,"Telemarketing"}, {1/4,"Inside Sales"}]).
  [ { 14400, "Input Needed" },
    { 3600,  "Web activity scoring", 0.25 },
    { 1200,  "Telemarketing",        0.3333333333333333 },
    { 300,   "Inside Sales",         0.25 },
    { 300,   "Result" } ]

Introduced in: Version 691

unfunnel/3

union/1

Untested Stoch untested

Introduced in: Version 586

union/2

Equivalent to union([L1, L2]).

Untested Stoch untested

Introduced in: Version 586

union/3

Equivalent to union([L1, L2, L3]).

Untested Stoch untested

Introduced in: Version 586

union/4

Equivalent to union([L1, L2, L3, L4]).

Untested Stoch untested

Introduced in: Version 586

unit_scale/1

Introduced in: Version 720

vector_magnitude/1

Equivalent to root_sum_square(VX).

Introduced in: Version 506

vector_normalize/1

Incomplete Untested Stoch untested Returns the magnitude of a vector. A vector's magnitude is the length of its hypoteneuse. A vector can be seen as the product of its unit vector and its magnitude; as such many people see a vector's magnitude as its scale. The normal of the zero vector is undefined, in the way that dividing by zero is undefined, and will throw an arithmetic exception.

  1> sc:vector_normalize([0,3,4]).
  [0.0,0.6,0.8]

Introduced in: Version 725

walk_unique_pairings/2

Untested Stoch untested

Introduced in: Version 547

weighted_arithmetic_mean/1

Untested Stoch untested Take the weighted arithmetic mean of the input values.

  1> sc:weighted_arithmetic_mean([ {8,1}, {3,4}, {16,1} ]).
  6.0

Introduced in: Version 484

See also: amean_vector_normal/1, arithmetic_mean/1.

zip_n/1

Equivalent to zip_n(Ls, to_tuple).

zip_n/2

Stoch untested Computes a zip on any sized group of lists, rather than just two or three as offered by the lists module.

  1> sc:zip_n([ [1,2,3], [a,b,c], [i,ii,iii] ]).
  [{1,a,i},{2,b,ii},{3,c,iii}]
 
  2> sc:zip_n([ [1,2,3], [a,b,c], [i,ii,iii], [x,y,z], [red,blue,green], [april,may,june] ]).
  [{1,a,i,x,red,april},
   {2,b,ii,y,blue,may},
   {3,c,iii,z,green,june}]

  3> Testy = [ [1,2,3], [1,2,3], [1,2,3] ].
  [[1,2,3],[1,2,3],[1,2,3]]
 
  4> sc:benchmark(sc, multi_do, [100000, sc, zip_n, [Testy]]).
  {174.95563, [[{1,1,1},{2,2,2},{3,3,3}], [{1,1,1},{2,2,2},{3,3,3}], ... }
 
  5> sc:benchmark(sc, multi_do, [100000, lists, zip3, Testy]).
  {149.605, [[{1,1,1},{2,2,2},{3,3,3}], [{1,1,1},{2,2,2},{3,3,3}], ... }

Introduced in: Version 472

zipf_estimate_list/1

Untested Stoch untested Estimates the zipf baseline from each number in a numeric list.

  1> sc:zipf_estimate_list([ 120, 60, 40, 30, 24, 20 ]).
  [120, 120, 120, 120, 120, 120]
 
  2> sc:zipf_estimate_list([411,198,135,101,82]).
  [411, 396, 405, 404, 410]
 
  3> sc:zipf_estimate_list([630,298,231,180,118]).
  [630, 596, 693, 720, 590]

Introduced in: Version 480

zipf_nearness/1

Untested Stoch untested todo.

  1> sc:zipf_nearness([ 120, 60, 40, 30, 24, 20 ]).
  [[ {strength,1.0}, {center,120.0} ],
   [ {strength,1.0}, {center,120.0} ],
   [ {strength,1.0}, {center,120.0} ],
   [ {strength,1.0}, {center,120.0} ],
   [ {strength,1.0}, {center,120.0} ],
   [ {strength,1.0}, {center,120.0} ]]
 
  2> sc:zipf_nearness([ 411, 198, 135, 101, 82 ]).
  [[{strength,0.9635036496350365}, {center,405.2}],
   [{strength,0.9658536585365854}, {center,403.75}],
   [{strength,0.9853658536585366}, {center,406.3333333333333}],
   [{strength,0.9853658536585366}, {center,407.0}],
   [{strength,1.0},                {center,410.0}]]
 
  3> sc:zipf_nearness([640,244,231,180,148]).
  [[{strength, 0.6594594594594595}, {center,656.2}],
   [{strength, 0.6594594594594595}, {center,660.25}],
   [{strength, 0.9364864864864865}, {center,717.6666666666666}],
   [{strength, 0.972972972972973},  {center,730.0}],
   [{strength, 1.0},                {center,740.0}]]

Introduced in: Version 480

zipf_position_estimate/2

Untested Stoch untested Estimates the zipf baseline from a score and a rank position.

  1> sc:zipf_position_estimate(120, 3).
  360

Introduced in: Version 480

Overview

Generated by EDoc, Jan 29 2012, 02:55:45.