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How do I shuffle an array randomly?

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How do I shuffle an array randomly?

Here's a shuffling algorithm which works its way through the list, randomly picking another element to swap the current element with:

    srand;
    @new = ();
    @old = 1 .. 10;  # just a demo
    while (@old) {
        push(@new, splice(@old, rand @old, 1));
    }

For large arrays, this avoids a lot of the reshuffling:

    srand;
    @new = ();
    @old = 1 .. 10000;  # just a demo
    for( @old ){
        my $r = rand @new+1;
        push(@new,$new[$r]);
        $new[$r] = $_;
    }

Source: Perl FAQ: Data Manipulation
Copyright: Copyright (c) 1997 Tom Christiansen and Nathan Torkington.

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