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math.statistics: Add docs for collect-by and collect-index-by.

db4
Doug Coleman 2013-02-05 09:28:37 -08:00
parent f4834ce51c
commit 18b7960e09
1 changed files with 33 additions and 0 deletions
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basis/math/statistics/statistics-docs.factor
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@ -236,6 +236,37 @@ HELP: rescale
{ $values { "u" sequence } { "v" sequence } }
{ $description "Returns " { $snippet "u" } " rescaled to run from 0 to 1 over the range min to max." } ;
HELP: collect-by
{ $values
{ "seq" sequence } { "quot" { $quotation "( obj -- ? )" } }
{ "hashtable" hashtable }
}
{ $description "Applies a quotation to each element in the input sequence and returns a " { $snippet "hashtable" } " of like elements. The keys of this " { $snippet "hashtable" } " are the output of " { $snippet "quot" } " and the values at each key are the elements that transformed to that key." }
{ $examples
"Collect even and odd elements:"
{ $example
"USING: math math.statistics prettyprint ;"
"{ 11 12 13 14 14 13 12 11 } [ odd? ] collect-by ."
"H{ { f V{ 12 14 14 12 } } { t V{ 11 13 13 11 } } }"
}
}
{ $notes "May be named " { $snippet "group-by" } " in other languages." } ;
HELP: collect-index-by
{ $values
{ "seq" sequence } { "quot" { $quotation "( obj -- ? )" } }
{ "hashtable" hashtable }
}
{ $description "Applies a quotation to each element in the input sequence and returns a " { $snippet "hashtable" } " of like elements. The keys of this " { $snippet "hashtable" } " are the output of " { $snippet "quot" } " and the values at each key are the indices for the elements that transformed to that key." }
{ $examples
"Collect even and odd elements:"
{ $example
"USING: math math.statistics prettyprint ;"
"{ 11 12 13 14 14 13 12 11 } [ odd? ] collect-index-by ."
"H{ { f V{ 1 3 4 6 } } { t V{ 0 2 5 7 } } }"
}
} ;
ARTICLE: "histogram" "Computing histograms"
"Counting elements in a sequence:"
{ $subsections
@ -291,6 +322,8 @@ ARTICLE: "math.statistics" "Statistics"
{ $subsections kth-smallest }
"Counting the frequency of occurrence of elements:"
{ $subsections "histogram" }
"Collecting related items:"
{ $subsections collect-by collect-index-by }
"Computing cumulative sequences:"
{ $subsections "cumulative" } ;