sample ( seq n -- seq' ) - Factor Documentation

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

Prev: randomize ( seq -- randomized )

Next: delete-random ( seq -- elt )

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 ;

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