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Re: Parsing an SQL table using an array of hashes?

by LanX (Bishop)
on Jun 28, 2013 at 20:54 UTC ( #1041344=note: print w/replies, xml ) Need Help??

in reply to Parsing an SQL table using an array of hashes?

An appropriate data structure would be


you could also go for


Now what is the real question?

How to get the input from SQL or how to get the output to GD::Graph ?

Cheers Rolf

(addicted to the Perl Programming Language)

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Re^2: Parsing an SQL table using an array of hashes?
by chareTX (Initiate) on Jun 29, 2013 at 00:53 UTC
    well, I was going to iterate through the data from SQL - I can already retrieve that. I was just confused on how to store and then retrieve the data. And yes, the next part of the problem will be how to arrange the data into the various series to give to GD::Graph.

      If you are likely to plot across years or over a period of say the last x months, then it may be convenient to convert your year and months into a 'period number'. Then you can store the data in a hash like this ;


      Storing a string of month/year in another array using the same period numbers as the index makes it easy to build the first record of your plot data.

      Here is an example of what I mean with your data expanded into 2014.

      #perl use strict; use GD::Graph; use GD::Graph::bars; my $YEAR1 = 2013; my @period=(); my %y_data=(); my @x_legend=(); # stroe data while (<DATA>){ chomp; my ($m,$y,$cat,$n) = split ',',$_; # convert year/month to period number my $pd = ym_to_pd($y,$m); $period[$pd] = "$m/$y"; $y_data{$cat}[$pd] = $n; } # graph data my @y_plotdata; push @y_plotdata,[@period]; for my $cat (sort keys %y_data){ push @x_legend,$cat; push @y_plotdata,[@{$y_data{$cat}}]; } # create graph my $my_graph = GD::Graph::bars->new(800,600); $my_graph->set( x_label => 'X Label', y_label => 'Y label', title => 'Title', ); $my_graph->set_legend(@x_legend); my $img = $my_graph->plot(\@y_plotdata) or die $my_graph->error; # save image open(IMG,'>','plot.gif') or die "$!"; binmode IMG; print IMG $img->png; close IMG; # convert year,month to period sub ym_to_pd { my ($yr,$mth) = @_; return ($yr - $YEAR1) * 12 + $mth; } # convert period to year.month sub pd_to_ym { my $ix = shift; my $yr = int(($ix-1)/12)+$YEAR1; my $mth = $ix-12*($yr-$YEAR1); return ($yr,$mth); } #test_periods(); sub test_periods { for my $y (2013..2015){ for my $m (1..12){ my $pd = ym_to_pd($y,$m); my ($yr,$mth) = pd_to_ym($pd); print "$y $m => $pd => $yr $mth\n"; } } } __DATA__ 3,2013,Address,1 2,2013,Equipment,13 3,2013,Equipment,18 4,2013,Equipment,17 5,2013,Equipment,8 3,2013,Database Reconciliation,3 5,2013,Database Reconciliation,3 2,2013,Design/Process,123 3,2013,Design/Process,74 4,2013,Design/Process,42 5,2013,Design/Process,30 1,2014,Design/Process,30
        Thank you very much -- this was very helpful. Two questions:

        1. Can you explain this line for me please? I am just not sure I get it.

         push @y_plotdata,[@{$y_data{$cat}}];

        2. I need to do the same thing, but reversed -- instead of category being the legend and dates on the x-axis, I need to do the categories on the a-axis, and the months in the legend.

        I haven't started experimenting with it yet, but I wanted to say thanks for your help.

        So, thanks for the excellent example. But, I now need to do it the other way. instead of having the categories in the legend, i need the categories on the x-axis and the periods in the legend. I think I can do that with the code you provided, but honestly, we are getting to the edge of my PERL knowledge.

      I never used GD::Graph, but if you need help you should

      a) read the docs / tutorials /search results

      b) show what you already tried

      c) identify your problems

      d) ask concrete questions, instead for complete solutions.

      We love teaching how to fish ... =)

      Cheers Rolf

      ( addicted to the Perl Programming Language)

        Can I get a free rod and hook?

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