in reply to More efficient Data Structure needed

This might work. It compiles clean but need your data to test it.

#! perl -slw use strict; my (@m_info, @data); #! Build a hash keyed by the first elements of the info data. my %m_info = map{ $_->[0] => $_ } @m_info; #! Build a (this|that|the other) regex from the search keys (Method by + [theDamian]). #! Updated to correct *my* errors when adapting [the Damian]'s code as + spotted by [Aristotle]++ below. my $regex = qr/(@{ [ join '|', map { "\Q$_\E" } keys %m_info ] })/; for my $record (@data) { if ( $record =~ $regex ) { #! $1 contains the key that matched. #! The corresponding array can be looked up from the hash my $info = $m_info{$1}; #! do the rest of your stuff #!$info->[3]... } }

Examine what is said, not who speaks.

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Re^2: More efficient Data Structure needed
by Aristotle (Chancellor) on Dec 18, 2002 at 12:16 UTC
    Very close, except for a few little mistakes: "(\Q$_)" must be "(\Q$_\E)", or else the closing paren will be escaped. But you don't want parens there anyway, it has to be one single capture group: my $rx =  qr/(@{[ join '|', map quotemeta, keys %m_info ]})/; Another, significantly more involved method that I first came up with when I encountered such a problem:
    my $rx = qr/@{ [ join '|', map "(\Q$_->[0]\E)", @m_info ] }/; for my $record (@data) { if (my @match = $record->[1] =~ $regex) { my ($m) = grep defined $match[$_], 0 .. $#match; $record->[1] = join "_", $m_info[$m]->[3], $m_info[$m]->[1]; } }
    The hash method is definitely preferrable though. Reasons to choose one over the other: a large @m_info will take less memory, a large %m_info will provide much faster lookups than the grep loop. So long as memory is not a constraint, the hash is the better choice as the code is both faster and more readable.

    Makeshifts last the longest.