New utility. Give it city-state-zip data in tab-separated format and it will give...

diff --git a/compile_zips b/compile_zips
new file mode 100755 (executable)
index 0000000..7cc9a58
--- /dev/null
+++ b/compile_zips
@@ -0,0 +1,33 @@
+#!/usr/bin/perl -w
+use strict;
+
+# Given input like "Miami Springs\tFL\t33166\n" derived from patron addresses,
+# this utility will print a city and state for each zip that has the maximum
+# number of occurrences. (It does not attempt to break ties. If there is a tie,
+# the city and state that reaches the maximum first will end up winning.)
+
+my %zips;
+
+# Go through the input and tally the city-state combinations for each ZIP code
+while (<>) {
+       chomp;
+       (my $city, my $state, my $zip) = split(/\t/) or next;
+       next unless $zip =~ m/([\d]{5})/; # If it doesn't have 5 digits in a row, it's not a ZIP
+       $zip =~ s/^([\d]{5}).*$/$1/;      # We only want the 5-digit ZIP
+       $state = uc($state);
+       $zips{$zip}{"$city\t$state"}++;
+}
+
+# Pick and print a winner for each ZIP code
+foreach(sort keys %zips) {
+       my $zip = $_;
+       my $max = 0;
+       my $citystate = "";
+       foreach(keys %{$zips{$zip}}) {
+               if ($zips{$zip}{$_} > $max) {
+                       $max = $zips{$zip}{$_};
+                       $citystate = $_;
+               }
+       }
+       print "$citystate\t$zip\n";
+}