Contributed by vroom
on Jan 17, 2000 at 09:16 UTC
Q&A
> numbers
Answer: How can I print all the numbers from 1 to n in random order? contributed by ChrisS I'd use the List::Util module.
use List::Util qw(shuffle);
my $n = 10; # use $ARGV[0] or whatever to set $n
print join " ", shuffle(1 .. $n);
 Answer: How can I print all the numbers from 1 to n in random order? contributed by btrott I don't see the original here, so I don't know
if this has been suggested... but you could
just stick the numbers in an array, then shuffle
the array, then print them. Use the FisherYates
Shuffle, which avoids the splice quadratic
algorithm bit.
sub fisher_yates_shuffle {
my $array = shift;
my $i;
for ($i = @$array; $i; ) {
my $j = int rand ($i+1);
next if $i == $j;
@$array[$i,$j] = @$array[$j,$i];
}
}
my $N = 50;
my @array = (1..$N);
fisher_yates_shuffle( \@array ); # permutes @array in place
print "@array";
From perlfaq4, How do I shuffle an array randomly?.  Answer: How can I print all the numbers from 1 to n in random order? contributed by lanval $ cat numbers.pl
#!/usr/bin/perl
sub RandomiseArray {
my (%b, $c);
map { do { $c = rand } until(!exists $b{$c}); $b{$c} = $_ } @_
+;
return values(%b);
}
my @a = RandomiseArray(1..10);
print "@a\n";
$ ./numbers.pl
8 5 1 3 10 2 6 4 9 7
$ ./numbers.pl
4 2 3 9 5 8 6 1 7 10
$ ./numbers.pl
8 10 7 6 5 9 2 3 4 1
Yeah?  Answer: How can I print all the numbers from 1 to n in random order? contributed by chromatic Hmm, see splice for why that doesn't work. Here's the fix:
print (splice @a, rand @a, 1); 
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