Same with "nicer" printout. 

#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11146593
use warnings;

my @copy = my @mapped = ("Account Entity Unit Jan Feb Mar",
            "Account01 Entity01 Unit01 1 2 3",
            "Account01 Entity01 Unit01 4 5 6",
            "Account01 Entity01 Unit01 7 8 9",
            "Account02 Entity02 Unit02 10 11 12");

my %group_by;
my @titles = split ' ', shift @mapped;

foreach (@mapped) {
    my %hash; @hash{ @titles } = split;   #don't get it NOTE makes a h
+ash with titles as keys and fields of current line as values
    for(qw(Jan Feb Mar)){
        $group_by{join ' ', @hash{qw(Account Entity Unit)}}{ $_ } += $
+hash{ $_ };    #don't get it either NOTE does the SUM function that y
+our SQL is doing
    }
}
#use Data::Dump 'dd'; dd \%group_by;

# if you want a "nice" printout

open my $incolumns, '|-', 'column -t' or die;
print $incolumns "$copy[0]\n", "$copy[0]\n" =~ s/\w/-/gr; # separator 
+line
foreach( sort keys %group_by )
  {
  print $incolumns "$_ @{ $group_by{ $_ } }{qw(Jan Feb Mar)}\n";
  }
close $incolumns;

[download]

Outputs: 

Account    Entity    Unit    Jan  Feb  Mar
-------    ------    ----    ---  ---  ---
Account01  Entity01  Unit01  12   15   18
Account02  Entity02  Unit02  10   11   12

[download]

In reply to Re^5: Group by from array by tybalt89
in thread Group by from array by sroux

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.