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Re: Replacing values in an array

by eyepopslikeamosquito (Canon)
on Jan 26, 2013 at 23:26 UTC ( #1015544=note: print w/ replies, xml ) Need Help??


in reply to Replacing values in an array

When dealing with duplicates in Perl, you should normally use a hash (perldoc -q duplicate). My solution (written before seeing toolic's) is essentially the same as his, though I excluded the check for "M" since all your test data contains "M".

use strict; use warnings; use Data::Dumper; my @array = ("M94202", "M94150", "M94297", "M94150", "M94161", "M94161 +", "M94162"); my %seen; my $z = 1; foreach my $item (@array) { if (exists $seen{$item}) { $item = $seen{$item}; } else { $seen{$item} = $z; $item = $z; $z += 2; } } print Dumper \@array; print "\n";


Comment on Re: Replacing values in an array
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Re^2: Replacing values in an array
by tonto (Pilgrim) on Jan 26, 2013 at 23:43 UTC
    Seeing the same solution written differently makes it more clear to me, I am very grateful to you. I will study hashes until I get them through my thick skull! I have spent days on this.
    Again, my sincere thanks!
    -tonto

      You can consider a hash to be much like an array, except instead of numerical indexes to access individual elements, you use strings as keys.

      # Define an array: my @basket = qw(apple banana cherry); # Get an element from the array: # (remember that indexes are 0-based) print "The second kind of fruit in the basket is $basket[1]\n"; # Change an element: $basket[1] = "date"; print "Now it is $basket[1]\n";

      The above example shouldn't be unfamiliar. Now, instead of keeping a @basket that tells us what kinds of fruit we have in the basket, let's keep a %basket that can also tell us how much of that kind of fruit we have.

      # Define the hash: my %basket = ( apple => 12, banana => 6, cherry => 32, # This final comma is optional, ); # but makes it easier to add more lines in the f +uture. # Get an element from the basket: print "There are $basket{cherry} cherries in the basket.\n"; # Modify elements: $basket{cherry}--; print "Now there are $basket{cherry}.\n"; $basket{banana} *= 2; print "Double Banana Bonus! $basket{banana} bananas in the basket!\n"; $basket{apple} = 10; # Add an element: $basket{date} = 16; # Get all keys in the hash: print "Fruits in my basket: ", join(", ", sort keys %basket), "\n"; # Using a variable as a key: for my $fruit (sort keys %basket) { print "You want a(n) $fruit? I have $basket{$fruit} in my basket.\ +n"; } # The 'each' function: while (my ($fruit, $amount) = each %basket) { print "There are $amount ${fruit}s in my basket.\n"; } # Getting rid of an element: delete $basket{apple}; print "Fruits in my basket: ", join(", ", sort keys %basket), "\n";

      That pretty much covers the basics of hashes. Nothing to be afraid of, and quite a useful data type!

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