A Divendres 15 Setembre 2006 22:21, D. Bolliger va escriure:
> Geetha Weerasooriya am Freitag, 15. September 2006 15:52:
> > Hi ,
> >
> > I have an Array of Hashes as follows:
> >
> > @array = (
> > { 'A'=>1, 'B' =>2, 'C'=>3, 'D'=>4}
> > { 'A'=>5, 'B' =>6, 'C'=>7, 'D'=>8}
> > { 'A'=>9, 'B' =>10, 'C'=>11, 'D'=>12}
> > { 'A'=>13, 'B' =>14, 'C'=>15, 'D'=>16}
> > { 'A'=>17, 'B' =>18, 'C'=>19, 'D'=>20}
> > { 'A'=>21, 'B' =>22, 'C'=>23, 'D'=>24}
> > )
> >
> > I have given a reference to this array in my script.
> >
> > I want to do some calculation with only one key of each hash. For
> > example, I want to subtract from the value of key 'B' of last hash all
> > the other values of the same key into a one column like follows
> >
> > 22-2 20
> > 22-6 16
> > 22-10 12
> > 22-14 8
> > 22-18 4
> > 22-22 0
> >
> > Can you please tell me how to do this ?
>
> Hi Geetha (again :-)
>
> Here's a slightly shorter version of J.W.Krahn's:
>
> #!/usr/bin/perl
>
> use strict;
> use warnings;
>
> my @array = (
> { A => 1, B => 2, C => 3, D => 4 },
> { A => 5, B => 6, C => 7, D => 8 },
> { A => 9, B => 10, C => 11, D => 12 },
> { A => 13, B => 14, C => 15, D => 16 },
> { A => 17, B => 18, C => 19, D => 20 },
> { A => 21, B => 22, C => 23, D => 24 },
> );
>
> # avoids multiple recalculation of the same value:
> #
> my $the_main_value=$array[ -1 ]->{ B };
>
>
> for my $hash ( @array ) {
> print $the_main_value - $hash->{ B }, "\n";
> }
>
> __END__
>
>
> Suppose you want to use this principle for several arrays, you can make a
> procedure:
>
> #!/usr/bin/perl
>
> use strict;
> use warnings;
>
> my @array = (
> #...
> );
>
>
> sub my_calculation {
> my $array_ref=shift;
>
> my $the_one_value=$array_ref->[ -1 ]->{ B };
>
> for my $hash ( @$array_ref ) {
> print $the_one_value - $hash->{ B }, "\n";
> }
> }
>
> my_calculation ([EMAIL PROTECTED]);
>
> __END__
>
> maybe you want to generalize the sub a bit:
>
> # ...
> sub my_calculation {
> my ($array_ref, $keyname)[EMAIL PROTECTED];
>
> my $the_one_value=$array_ref->[ -1 ]->{ $keyname };
>
> for my $hash ( @$array_ref ) {
> print $the_one_value - $hash->{ $keyname }, "\n";
> }
> }
> # ...
> my_calculation ([EMAIL PROTECTED], 'B');
>
> __END__
>
> greets
>
> Dani
To access an elements of an array of hashes, do like:
print $array[4]{A},"\n"; #is value 17.
--
Xavier Mas
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