If the probabilities precision is limited to 2 digits as for your sample data: 
my %odds = (a => 0.1, b => 0.5, c => 0.4 );

my @dize = map { ($_) x int(100 * $odds{$_}) } keys %odds;

for (1..1000) {
  print $dize[rand @dize], "\n";
}

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In reply to Re: How do I get a random index with weighting? by salva
in thread How do I get a random index with weighting? by m_al

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