Re: Pulling random elements from hash

[sgifford]

You'd probably be better served by an array for this, where you could just do:

$array[int(rand(scalar(@array)))];

to choose a random element.

You can do much the same thing, though, by pulling the hash keys into a list and choosing one randomly:

$hk = (keys %hash)[int(rand(scalar(keys %hash)))];
$hv = $hash{$hk};

If you'll do it often, pull the keys into an array and just use that:

@arr = keys %hash;
$hk = $arr[int(rand(scalar(@arr)))];
$hv = $hash{$hk};

With both of the hash solutions, you end up with two copies of all the keys, so it's less memory-efficient than an array, but probably fine if you have a few thousand entries or less.

[Aristotle]

$array[int(rand(scalar(@array)))];

Of course you can just write

$array[rand @array];

which will do exactly the same thing and is a bit less distracting to read.

Makeshifts last the longest.

[sgifford]

I saw that in another post. Do you know why this is? It seems like rand is unlikely to pick an integer, and $array[3.14159] seems nonsensical, but I tried it and it works...

[merlyn]

Whenever Perl needs an integer, and is provided a floating-point value instead, Perl automatically truncates. This is universal.

-- Randal L. Schwartz, Perl hacker
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