[Chicago-talk] Combine like hash elements

[Alan Mead]

Richard,

So, you want the new hash to have fewer elements.  There may be an
idiomatic way, but the straightforward way would be to cycle through
your old hash building a new hash of totals. Let's say your hash is
%trans, then:

my %total_trans;
for my $k ( keys %trans) {
  my $name = $$trans{$k}->{'NAME'}; # check if this is right
  my $amount = $$trans{$k}->{'AMOUNT'}; # check if this is right
  $total_trans{$name} += $amount;
}
printf "%.2f\n", $total_trans{'Lincoln Park'}; # prints 38.00

You'll have to check the two temporary variables to ensure I
dereferenced them correctly and then you could factor them out.  You
could modify this so the new hash has the same structure as the old hash.

I think this would be clearer than trying to edit the original hash.
Pity your data are not in a database where this would be a simple
database call.

-Alan


On 11/23/2015 10:10 AM, richard at rushlogistics.com wrote:
> I have a hash reference with the following structure:
>
> {
> '11' => {'AMOUNT' => '20.00','ID' => '11','NAME' => 'Lincoln Park'},
> '12' => {'AMOUNT' => '38.00','ID' => '12','NAME' => 'Bucktown'},
> '13' => {'AMOUNT' => '41.00','ID' => '12','NAME' => 'Lincoln Park'}
> }
>
> Can anyone tell me how I can combine them by 'NAME' so that I would have:
>
> {
> '11' => {'AMOUNT' => '61.00','ID' => '11','NAME' => 'Lincoln Park'},
> '12' => {'AMOUNT' => '38.00','ID' => '12','NAME' => 'Bucktown'},
> }
>
> Thanks
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Alan D. Mead, Ph.D.
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