Re: random number with range

[Enlil]

in reply to random number with range

my @range = ( 50 .. 200 );
my $random_number = $range[rand(@range)];

[GrandFather]

An interesting way to do it. But expensive in memory and time for large ranges. Consider:

my @range = ( -1_000_000 .. 1_000_000 );
my $random_number = $range[rand(@range)];

which takes about 1/2 a second and has about a 100 MB dynamic memory requirement.

[ikegami]

Indeed, but the technique is particularly useful for sets. For example,

my @set = ( 1, 2, 3, 5, 8, 13, 21 );
my $random = $set[rand(@set)];

my @set = qw( apple orange banana cucumber );
my $random = $set[rand(@set)];

[Enlil]

won't disagree, but first thing that came to mind for similar situations where the technique is useful, like the ubiquitous password generator:

my @chars = ( 'A' .. 'Z', 0 .. 9);
my $pw = join('',@chars[ map { rand @chars } ( 1 .. 12 ) ]);