[Chicago-talk] Combine like hash elements

[imran javaid]

You could also push the aggregation to the DB server and have it do the sum
by name.

On Mon, Nov 23, 2015 at 12:52 PM, <richard at rushlogistics.com> wrote:

> Hello Everybody,
>
>
>
> Thank you for all the replies. The ID field did not need to be preserved.
> However, I was having difficulty conceptualizing the manipulation of the
> hash so I decided to use DBI->bind_colums instead and iterate throught the
> values in a way that I found at least a bit more clear. Still working on
> cleaning this up but this is at least the direction that I am going in.
>
>
>
> Thanks again for the help.
>
>
>
>    my ($DID, $AMOUNT, $NAME,);
>     $sth->bind_columns(\($DID, $AMOUNT, $NAME));
>
> my $lastN;
> my $lastA;
> my @CAMS;
> my $keepN;
> my $keepA;
>
> while ($sth->fetch) {
>
> if ($lastN) {
>
>     if ($NAME eq $lastN) {
>
>     #print "Combine $AMOUNT, $NAME\n";
>     $keepA = $AMOUNT + $lastA;
>     $keepN = $NAME;
>
>     } else {
>
>     $keepA = $AMOUNT;
>     $keepN = $NAME;
>
>     }
>
> }
>
> # print "$DID, $AMOUNT, $NAME\n";
>
> $lastN = $NAME;
> $lastA = $AMOUNT;
>
> push(@CAMS, $keepA . " " . $keepN);
>
>
> }
>
>
> On Mon, 23 Nov 2015 11:28:40 -0600, Steven Lembark <lembark at wrkhors.com>
> wrote:
>
> On Mon, 23 Nov 2015 10:10:41 -0600
> 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'},
> > }
>
> You don't seem to care about the keys (loosing key "13" wasn't
> a problem).
>
> Q: Are the ID values important or could they be discarded?
>
> If so then just make a new hash keyed by NAME and accumulate
> the AMOUNT values:
>
> my %resultz = ();
>
> for( values %inputz )
> {
> my ( $name, $amt, $id ) = @{ $_ }{ qw( NAME AMOUNT ID ) };
> my $val
> = $resultz{ $name } ||= { ID => $id, NAME => $name };
>
> $val->{ AMOUNT } += $amt;
> }
>
> # at this point %resultz is keyed by name with an id and amount
> # for each entry.
>
> %inputz = ();
>
> while( my ( $name, $val ) = each %resultz )
> {
> $inputz{ $val->{ ID } } = $val;
> }
>
> # at this point the original inputs hash is keyed by ID
> # with values having a name, accumulated amount, and id.
> # multiple id's are collapsed into a single ID with the
> # value of the first record for that name.
>
> --
> Steven Lembark 3646 Flora Pl
> Workhorse Computing St Louis, MO 63110
> lembark at wrkhors.com +1 888 359 3508
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>
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