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Remove documentation duplication in math.statistics

db4
Aaron Schaefer 2008-11-18 10:30:11 -05:00
parent c3f05eaaa1
commit 47d268d894
2 changed files with 7 additions and 14 deletions
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11
extra/math/statistics/statistics-docs.factor
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@ -3,13 +3,14 @@ IN: math.statistics
HELP: geometric-mean
{ $values { "seq" "a sequence of numbers" } { "n" "a non-negative real number"} }
{ $description "Computes the geometric mean of all elements in " { $snippet "seq" } ". The geometric mean measures the central tendency of a data set that minimizes the effects of extreme values." }
{ $description "Computes the geometric mean of all elements in " { $snippet "seq" } ". The geometric mean measures the central tendency of a data set that minimizes the effects of extreme values." }
{ $examples { $example "USING: math.statistics prettyprint ;" "{ 1 2 3 } geometric-mean ." "1.81712059283214" } }
{ $errors "Throws a " { $link signal-error. } " (square-root of 0) if the sequence is empty." } ;
HELP: harmonic-mean
{ $values { "seq" "a sequence of numbers" } { "n" "a non-negative real number"} }
{ $description "Computes the harmonic mean of the elements in " { $snippet "seq" } ". The harmonic mean is appropriate when the average of rates is desired." }
{ $description "Computes the harmonic mean of the elements in " { $snippet "seq" } ". The harmonic mean is appropriate when the average of rates is desired." }
{ $notes "Positive reals only." }
{ $examples { $example "USING: math.statistics prettyprint ;" "{ 1 2 3 } harmonic-mean ." "6/11" } }
{ $errors "Throws a " { $link signal-error. } " (divide by zero) if the sequence is empty." } ;
@ -36,21 +37,21 @@ HELP: range
HELP: std
{ $values { "seq" "a sequence of numbers" } { "x" "a non-negative real number"} }
{ $description "Computes the standard deviation of " { $snippet "seq" } " by squaring the variance of the sequence. It measures how widely spread the values in a sequence are about the mean." }
{ $description "Computes the standard deviation of " { $snippet "seq" } ", which is the square root of the variance. It measures how widely spread the values in a sequence are about the mean." }
{ $examples
{ $example "USING: math.statistics prettyprint ;" "{ 1 2 3 } std ." "1.0" }
{ $example "USING: math.statistics prettyprint ;" "{ 1 2 3 4 } std ." "1.290994448735806" } } ;
HELP: ste
{ $values { "seq" "a sequence of numbers" } { "x" "a non-negative real number"} }
{ $description "Computes the standard error of the mean for " { $snippet "seq" } ". It's defined as the standard deviation divided by the square root of the length of the sequence, and measures uncertainty associated with the estimate of the mean." }
{ $description "Computes the standard error of the mean for " { $snippet "seq" } ". It's defined as the standard deviation divided by the square root of the length of the sequence, and measures uncertainty associated with the estimate of the mean." }
{ $examples
{ $example "USING: math.statistics prettyprint ;" "{ -2 2 } ste ." "2.0" }
{ $example "USING: math.statistics prettyprint ;" "{ -2 2 2 } ste ." "1.333333333333333" } } ;
HELP: var
{ $values { "seq" "a sequence of numbers" } { "x" "a non-negative real number"} }
{ $description "Computes the variance of " { $snippet "seq" } ". It's a measurement of the spread of values in a sequence. The larger the variance, the larger the distance of values from the mean." }
{ $description "Computes the variance of " { $snippet "seq" } ". It's a measurement of the spread of values in a sequence. The larger the variance, the larger the distance of values from the mean." }
{ $notes "If the number of elements in " { $snippet "seq" } " is 1 or less, it outputs 0." }
{ $examples
{ $example "USING: math.statistics prettyprint ;" "{ 1 } var ." "0" }

10
extra/math/statistics/statistics.factor
View File

@ -5,20 +5,15 @@ USING: arrays combinators kernel math math.analysis math.functions sequences
IN: math.statistics
: mean ( seq -- n )
#! arithmetic mean, sum divided by length
[ sum ] [ length ] bi / ;
: geometric-mean ( seq -- n )
#! geometric mean, nth root of product
[ length ] [ product ] bi nth-root ;
: harmonic-mean ( seq -- n )
#! harmonic mean, reciprocal of sum of reciprocals.
#! positive reals only
[ recip ] sigma recip ;
: median ( seq -- n )
#! middle number if odd, avg of two middle numbers if even
natural-sort dup length even? [
[ midpoint@ dup 1- 2array ] keep nths mean
] [
@ -26,11 +21,10 @@ IN: math.statistics
] if ;
: range ( seq -- n )
#! max - min
minmax swap - ;
: var ( seq -- x )
#! variance, normalize by N-1
#! normalize by N-1
dup length 1 <= [
drop 0
] [
@ -39,11 +33,9 @@ IN: math.statistics
] if ;
: std ( seq -- x )
#! standard deviation, sqrt of variance
var sqrt ;
: ste ( seq -- x )
#! standard error, standard deviation / sqrt ( length of sequence )
[ std ] [ length ] bi sqrt / ;
: ((r)) ( mean(x) mean(y) {x} {y} -- (r) )