sample ( seq n -- seq' )
Generating random integers

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Vocabulary
random

Inputs

seq	a sequence
n	an integer

Outputs

seq'	a sequence

Word description
Takes n samples at random without replacement from a sequence. Throws an error if n is longer than the sequence.

Examples

USING: random prettyprint ; { 1 2 3 } 2 sample .
{ 3 2 }

Definition

USING: arrays kernel math sequences sequences.private ;

IN: random

: sample ( seq n -- seq' )
    2dup [ length ] dip < [ too-many-samples ] when [
        [ length <iota> >array ] dip [ randomize-n-last ] keep
        tail-slice*
    ] [ drop ] 2bi nths-unsafe ;