random* ( obj rnd -- elt )

Vocabulary

random

Inputs

obj	an object
rnd	a random number generator

Outputs

elt	a random element

Word description

Outputs a random element of the input object, or outputs f if the object contains no elements.

See also

random, randoms

Definition

IN: random

GENERIC#: random* 1 ( obj rnd -- elt )

Methods

USING: assocs kernel random ;

M: assoc random* [ >alist ] dip random* ;


USING: math random random.private ;

M: bignum random* random-integer ;


USING: math random random.private ;

M: fixnum random* random-integer ;


USING: kernel math random random.private ;

M: float random*
    [ f ] swap [ [ 0.0 ] ] dip [ (uniform-random-float) ] curry
    compose if-zero ; inline


USING: accessors hash-sets hashtables.private kernel math random
sequences.private sets ;

M: hash-set random*
    [ dup cardinality [ drop f ] ] dip [ random* ] curry
    [ [ [ 0 ] [ array>> ] ] ] dip [
        tri* 1 +
        [ [ 2dup array-nth tombstone? [ 1 + ] 2dip ] loop ]
        times [ 1 - ] dip array-nth
    ] curry compose if-zero ;


USING: accessors arrays assocs hashtables hashtables.private
kernel math random sequences.private ;

M: hashtable random*
    [ dup assoc-size [ drop f ] ] dip [ random* ] curry
    [ [ [ 0 ] [ array>> ] ] ] dip [
        tri* 1 +
        [ [ 2dup array-nth tombstone? [ 2 + ] 2dip ] loop ]
        times [ 2 - ] dip
        [ array-nth ] [ [ 1 + ] dip array-nth ] 2bi 2array
    ] curry compose if-zero ;


USING: kernel random sequences ;

M: sequence random*
    [ f ] swap [ [ length ] ] dip [ random* ] curry compose
    [ keep nth ] curry if-empty ;


USING: kernel random sets ;

M: set random* [ members ] dip random* ;


USING: accessors kernel kernel.private math math.extras random
random.private sequences.private ;

M:: vose random* ( obj rnd -- elt )
    obj n>> rnd random* { fixnum } declare
    dup obj probs>> nth-unsafe { float } declare
    rnd (random-unit) >=
    [ obj alias>> nth-unsafe { fixnum } declare ] unless
    obj items>> nth-unsafe ;