Randomizing a list 
Author Message
 Randomizing a list

  Given a list of items.

              How do i create a new list with a random order or
             the initial list?

              Thanks

                Doron.



Wed, 24 Dec 2003 01:28:18 GMT  
 Randomizing a list

Quote:

>   Given a list of items.
>               How do i create a new list with a random order or
>              the initial list?

See the section "How do I shuffle an array randomly?" in perlfaq4.


Wed, 24 Dec 2003 00:51:36 GMT  
 Randomizing a list

Quote:

>   Given a list of items.

>               How do i create a new list with a random order or
>              the initial list?

#!/usr/bin/perl -w
use strict;

$, = " ";


for(0..100){



Quote:
}


__END__

output :
before :  1 2 3 4 5 6 7 8 9
after :  5 6 3 7 8 9 1 4 2

The number of iterations necessary for a truly randomisation is
debatable.  I use 100 here as a proof of principle.

HTH

Paul



Wed, 24 Dec 2003 00:58:39 GMT  
 Randomizing a list

Quote:

>Snip post>
> The number of iterations necessary for a truly randomisation is
> debatable.  I use 100 here as a proof of principle.

Ahem.  Pardon my English...  I meant "for true randomisation".  It's
been a long day...  who would have thought that English was my first
language?

Sorry.

Paul



Wed, 24 Dec 2003 01:03:03 GMT  
 Randomizing a list

Quote:

>   Given a list of items.

>               How do i create a new list with a random order or
>              the initial list?

>               Thanks

>                 Doron.

Sounds like an FAQ:

perldoc -q random

Read for "How do I shuffle an array randomly?"

--
Tim Schmelter
Public Key available from http://www.keyserver.net
CAD7 2ABB 05A4 2F00 4CAE 7D2F 127C 129A 7173 2951



Wed, 24 Dec 2003 01:16:56 GMT  
 Randomizing a list


Quote:
>The number of iterations necessary for a truly randomisation is
>debatable.

No, it isn't.  It's mathematical fact.

Quote:
>  I use 100 here as a proof of principle.

Even 100 is not enough for unbiased shuffling with this algorithm.
Unless the list has fewer than 3 elements, this algorithm always
produces a biased shuffle.

rd
($p{$_})&6];$p{$_}=/ ^$P/ix?$P:close$_}keys%p}p;p;p;p;p;map{$p{$_}=~/^[P.]/&&
close$_}%p;wait until$?;map{/^r/&&<$_>}%p;$_=$d[$q];sleep rand(2)if/\S/;print



Thu, 25 Dec 2003 01:53:01 GMT  
 
 [ 6 post ] 

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