in reply to Re: Select three random numbers between 1..10
in thread Select three random numbers between 1..10

perl -le '@n=(1..10);while(@l<3){push@l, splice@n,int rand@n,1}print for@l'


-Waswas

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Re: Re: Re: Select three random numbers between 1..10
by waswas-fng (Curate) on Mar 16, 2004 at 21:50 UTC
    or... perl -le '@l=sort{rand$_<=>rand$_}(1..10);print for@l[0..2]]'


    -Waswas
[reply]
[d/l]
      perl -le '@l=sort{rand$_<=>rand$_}(1..10);print for@l[0..2]'

      [download]
      In older Perls, it's not garanteed to give any meaningful results - in fact, perl might as well segfault. In modern Perls, about all that's garanteed is that perl won't segfault, and perl won't internally get corrupted. I'm not at all convinced that the above code produces fair results. Here's a test with a smaller array that strongly suggests your algorithm isn't fair: 
      #!/usr/bin/perl

use strict;
use warnings;
no warnings qw /syntax/;

my @array = (1 .. 4);
my %count;
my $mult  = 10_000;

for (1 .. 24 * $mult) {
    my @t = sort {rand 1 <=> rand 1} @array;
    $count {"@t"} ++;
}

foreach my $key (sort keys %count) {
    printf "%5d: %s\n" => $count {$key}, $key
}

__END__
15063: 1 2 3 4
15069: 1 2 4 3
 7419: 1 3 2 4
 7615: 1 3 4 2
 7602: 1 4 2 3
 7606: 1 4 3 2
14978: 2 1 3 4
14923: 2 1 4 3
 7497: 2 3 1 4
 7460: 2 3 4 1
 7558: 2 4 1 3
 7401: 2 4 3 1
 7485: 3 1 2 4
 7484: 3 1 4 2
 7585: 3 2 1 4
 7577: 3 2 4 1
14876: 3 4 1 2
14968: 3 4 2 1
 7467: 4 1 2 3
 7544: 4 1 3 2
 7461: 4 2 1 3
 7477: 4 2 3 1
14853: 4 3 1 2
15032: 4 3 2 1

      [download]

      Abigail

[reply]
[d/l]
[select]
        When golfing... (I did not really care about old perl compatibility)

        A quick trip to the sort perldoc exposes me to: 
              The comparison function is required to behave.  If it returns
      inconsistent results (sometimes saying $x[1] is less than $x[2]
      and sometimes saying the opposite, for example) the results are
      not well-defined.

        [download]


        So i guess my golf does not produce completely random picks thanks for the heads up... ohh well =)


        -Waswas
[reply]
[d/l]

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