functional programming: sort to shuffle

[stefp]

It shuffles the parameters list:

sub shuffle { map { @_=sort { int (3*rand)-1 } @_ } 0..5 }

Note that I go thru 6 iterations to get "sufficient" disorder.

see Why I like functional programming by tilly.

-- stefp

[demerphq]

Cool idea. stefp++.
Curious if sort could get into a 'never finish' scenario if the right values came up from rand though?
Thought you might like this version of the fisher yates shuffle.


sub fy_shuf{my($l,$c,$r)=@_;map{$r=int(rand($_+1));
@$l[$_,$r]=@$l[$r,$_]}reverse 0..$#$l for 0..$c||0};

my @a=(1..52);
fy_shuf(\@a,5);

UPDATE
Having had a look at japhy home node I borrowed an idea from him and reduced it more. (Oh and I decided that shuffling mutiple times was unecessary.)

sub fy_shuf{my($l,$r)=@_;map{$r=int(rand(@$l-$_+1));@$l[-$_,$r]=@$l[$r
+,-$_]}0..$#$l};

Yves
--
You are not ready to use symrefs unless you already know why they are bad. -- tadmc (CLPM)

[stefp]

It really depends on the internal sort algorithm. The "never finish" scenario is not the worse possible one: on some old versions of perl, my shuffle function crashes the perl interpretor :)

That is why this really belongs to the obfuscation category... to answer a remark on the CB.

Anyway, on 5.6, it works fine and dandy.

-- stefp