drose2211:

Sure thing: you can use a hash to hold an array of digit entries for each city you encounter, like this:

$ cat pm1207805.pl
#!usr/bin/perl
use strict;
use warnings;
use Text::CSV;
use List::Util qw(sum);
use Data::Dumper;

my $csv = Text::CSV->new();
my $FH = \*DATA;
my %accumulator;

# Gather the digits for the cities
while (my $row = $csv->getline($FH)) {
    my $city = $row->[1];
    my $digits = $row->[3];
    push @{$accumulator{$city}}, $digits;
}

# What do we have to work with?
print "Data:\n", Dumper(\%accumulator), "\n\n";

# Dump our results
for my $city (sort keys %accumulator) {
    my $num_rows = @{$accumulator{$city}};
    print "$city: ", sum(@{$accumulator{$city}}) / $num_rows, "\n";
}

__DATA__
CA006139520,"WINDSOR RIVERSIDE, ON CA",2018-01-02,10
CA006139520,"WINDSOR RIVERSIDE, ON CA",2018-01-02,20
CA006139520,"WINDSOR RIVERSIDE, ON CA",2018-01-02,14
CA006138520,"NEW YORK",2018-01-02,11
CA006137520,"PHILADELPHIA, ON CA",2018-01-02,23
CA006137520,"PHILADELPHIA, ON CA",2018-01-02,25
CA006138520,"NEW YORK",2018-01-02,13
CA006138520,"NEW YORK",2018-01-02,19
[download]

When you run it, you should get:

$ perl pm1207805.pl
Data:
$VAR1 = {
          'WINDSOR RIVERSIDE, ON CA' => [
                                          '10',
                                          '20',
                                          '14'
                                        ],
          'PHILADELPHIA, ON CA' => [
                                     '23',
                                     '25'
                                   ],
          'NEW YORK' => [
                          '11',
                          '13',
                          '19'
                        ]
        };


NEW YORK: 14.3333333333333
PHILADELPHIA, ON CA: 24
WINDSOR RIVERSIDE, ON CA: 14.6666666666667
[download]

...roboticus

When your only tool is a hammer, all problems look like your thumb.

... multiple names I am attempting to match. ... Just added if statements in the while loop.

if-statement patches are probably ok for one-off or infrequent runs with a small, stable city-name list. For larger lists of cities or more frequent runs, I think I would go with a database.

It's also possible to use a regex/hash approach:

c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"my @cities = ('windsor riverside', ' new york ', 'philadelphia',);
 ;;
 my $rx_city = build_city_regex(@cities);
 print $rx_city;
 ;;
 my %city_digits;
 ;;
 RECORD:
 for my $record (
     'CA006139520,\"WINDSOR RIVERSIDE, ON CA \",2018-01-02,10',
   qq{CA006139520,\"  NEW  YORK  , ON CA \",2018-01-02,987\n},
     'CA006139520,\"NEWYORK, ON CA \",2018-01-02,9999',
     'CA006139520,\"NEW YORK, ON CA \",2018-01-02,10210',
   qq{CA006139520,\"PHILADELPHIA, ON CA \",2018-01-02,76\n},
   ) {
   next RECORD unless
     my ($city, $digits) = $record =~ m{ ($rx_city) .* \b (\d+) \Z }xm
+s;
   push @{ $city_digits{ canonicalize_city($city) } }, $digits
   }
 dd \%city_digits;
 ;;
 sub build_city_regex {
   my ($regex) =
     map  qr{ \b (?: $_) \b }xms,
     join ' | ',
     map  { (my $c = $_) =~ s{ \s+ }'\s+'xmsg;  $c; }
     reverse sort
     map  canonicalize_city($_),
     @_
     ;
   return $regex;
   }
 ;;
 sub canonicalize_city {
   my ($city_name) = @_;
   ;;
   die qq{bad city: '$city_name'}
     if $city_name =~ m{ [^[:alpha:] -] }xms;
   $city_name =~ s{ \A \s+ | \s+ \z }''xmsg;
   $city_name =~ s{       \s+       }' 'xmsg;
   $city_name = uc $city_name;
   ;;
   return $city_name;
   }
"
(?msx-i: \b (?: WINDSOR\s+RIVERSIDE | PHILADELPHIA | NEW\s+YORK) \b )
{
  "NEW YORK"          => [987, 10210],
  PHILADELPHIA        => [76],
  "WINDSOR RIVERSIDE" => [10],
}
[download]