reservoir-sample-iteration ( iteration k obj sampled -- sampled' )
Reservoir Sampling

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reservoir-sample ( obj sampler -- )

Vocabulary
reservoir-sampling

Inputs

iteration	an integer
k	an integer
obj	an object
sampled	a vector

Outputs

sampled'

a vector

Word description
Sample with equal probabilty without using a reservoir-sampler object.

Definition

USING: kernel math random sequences ;

IN: reservoir-sampling

: reservoir-sample-iteration
    ( iteration k obj sampled -- sampled' )
    pick over length >
    [ [ push ] keep 2nip ] [
        roll random roll dupd <
        [ swap [ set-nth ] keep ] [ drop nip ] if
    ] if ;