Hello haukex,

just for fun a solution exploiting the randomness of hash keys.

   hkey => sub{
        my @range = (keys %{+{map {($_ => 1)}0 .. $N-1}})[0 .. $K-1];
   }

[download]

It is slightly faster than samp for very small sets..

perl randomshuffle.pl 10 5
          Rate  samp  hkey  shuf   mpu
samp  108393/s    --  -13%  -88%  -92%
hkey  124178/s   15%    --  -87%  -90%
shuf  934174/s  762%  652%    --  -27%
mpu  1275273/s 1077%  927%   37%    --

[download]
..but becomes fastly slower ;) for bigger ones. 
 
perl randomshuffle.pl 100 5
          Rate  hkey  samp  shuf   mpu
hkey   15844/s    --  -46%  -93%  -99%
samp   29546/s   86%    --  -86%  -98%
shuf  212991/s 1244%  621%    --  -86%
mpu  1519656/s 9491% 5043%  613%    --

[download]

The only thing to note is the %{+{ LIST }} syntax, where + is used to disambiguate a hashref from a block (credit: perl IRC channel) because you can't dereference a map as a hash.

PS: your hardware is ~3 times faster than mine ;)

PPS: "randperm" is not exported by the Math::Prime::Util module in 0.60 so i upgraded to 0.73

L*

There are no rules, there are no thumbs..
Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.

In reply to Re^3: Pick k numbers at random -- hash keys by Discipulus
in thread Pick k numbers at random by Chuma

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