hash sorting/alphabetization issue : country postal codes

hmbscully has asked for the wisdom of the Perl Monks concerning the following question:

Here's the scenario:
I receive text files on a regular basis. One file for each country named by XX.txt where 'XX' is the two letter country code. The complete list of the countries I have files for changes regularly. I need an <option> list that corresponds to the available countries.

I have a hash of all the country codes and the country names
A bit of that hash:

%country_names = (
     "AF" => "Afghanistan",
     "AX" => "Aland Islands",
     "AL" => "Albania",
     "DZ" => "Algeria",
     "AS" => "American Samoa",
     "AD" => "Andorra",
     "AO" => "Angola",
     "AI" => "Anguilla",
     "AQ" => "Antarctica",
     "AG" => "Antigua And Barbuda",
     "AR" => "Argentina",
     "AM" => "Armenia",
     "AW" => "Aruba",
     "AU" => "Australia",
     "AT" => "Austria",
     "AZ" => "Azerbaijan",
     "BS" => "Bahamas",
     "BH" => "Bahrain",
     "BD" => "Bangladesh",
     "BB" => "Barbados",
);
[download]

ect...

What I want to do is this:

opendir(ODIR, "$sr_data/f") || die ("Unable to open directory $sr_data
+/f");
        @intl_files = grep !/^\./, readdir ODIR; #this line gets rid o
+f . and ..
        closedir ODIR;        
        open(FILE,">$includes_codes_dir/sc_intl_dd.txt"); 
          foreach $file (sort @intl_files) { 
                $file =~ s/\.\w+$//; #remove the extension
              print FILE "<option value=\"$file\">$country_names{$file
+}</option>\n"; 
          }
          close(FILE);
[download]

Which does build me an option list, but the problem is that the option items are in alphabetical order based on the country codes, not the country names. I know it has to do with ordering somewhere along the line, but I'm just having trouble seeing the logic.

Make any sense?
Thanks.

I learn more and more about less and less until eventually I know everything about nothing.

Comment on hash sorting/alphabetization issue : country postal codes Select or Download Code

Replies are listed 'Best First'.
Re: hash sorting/alphabetization issue : country postal codes by grep (Monsignor) on Jul 03, 2007 at 19:40 UTC
Send `sort` the hash values not the keys. #!/usr/bin/perl use warnings; use strict; my %country_names = ( "AF" => "Afghanistan", "AX" => "Aland Islands", "AL" => "Albania", "DZ" => "Algeria", "AS" => "American Samoa", "AD" => "Andorra", "AO" => "Angola", "AI" => "Anguilla", "AQ" => "Antarctica", "AG" => "Antigua And Barbuda", "AR" => "Argentina", "AM" => "Armenia", "AW" => "Aruba", "AU" => "Australia", "AT" => "Austria", "AZ" => "Azerbaijan", "BS" => "Bahamas", "BH" => "Bahrain", "BD" => "Bangladesh", "BB" => "Barbados", "ZZ" => "AAAAAAA" ); my @sorted_keys = sort { $country_names{$a} cmp $country_names{$b} } k +eys %country_names; print join("\n",@sorted_keys); [download] grep	[reply] [d/l] [select]
Re^2: hash sorting/alphabetization issue : country postal codes by parv (Parson) on Jul 03, 2007 at 20:24 UTC
`my @sorted_keys = sort { $country_names{$a} cmp $country_names{$b} } k +eys %country_names;` [download] Considering that in the end you would have sorted VALUES not the keys, above array variable name is rather misleading. Correction. Afer grep's reply below, I saw that what was misleading was my claim made above. The array name was reasonable; it was my fault for forgetting that sort sorted the LIST based on result of BLOCK.	[reply] [d/l]
Re^3: hash sorting/alphabetization issue : country postal codes by grep (Monsignor) on Jul 03, 2007 at 21:36 UTC
Considering that in the end you would have sorted VALUES not the keys, above array variable name is rather misleading. I disagree - `@sorted_keys` contains SORTED KEYS, sorted by the values. But feel free to call it `@keys_sorted_by_value` if you feel like it. grep	[reply] [d/l] [select]
Re^4: hash sorting/alphabetization issue : country postal codes by parv (Parson) on Jul 04, 2007 at 04:43 UTC
Re^2: hash sorting/alphabetization issue : country postal codes by hmbscully (Scribe) on Jul 03, 2007 at 19:59 UTC
The hash is already in alphabetical order by the values. I sorted those first thing. I learn more and more about less and less until eventually I know everything about nothing.	[reply]
Re^3: hash sorting/alphabetization issue : country postal codes by grep (Monsignor) on Jul 03, 2007 at 20:05 UTC
Hashes are not ordered (well in any order you care about). So I don't quite know what you are referring to. but the problem is that the option items are in alphabetical order based on the country codes, not the country names. Am I not understanding what you meant by that? grep	[reply]
Re: hash sorting/alphabetization issue : country postal codes by rhesa (Vicar) on Jul 03, 2007 at 19:37 UTC
You can sort by the country name, instead of the code: `sort { $country_names{$a} cmp $country_names{$b} } @intl_files` [download] See sort for the details.	[reply] [d/l]
Re: hash sorting/alphabetization issue : country postal codes by FunkyMonk (Bishop) on Jul 03, 2007 at 19:56 UTC
my %country_names = ( "AF" => "Afghanistan", "AX" => "Aland Islands", "AL" => "Albania", "DZ" => "Algeria", "AS" => "American Samoa", "AD" => "Andorra", ); my @intl_files = <DATA>; chomp @intl_files; # not needed when using opendir/readdir #map removes the ".txt" file suffix #sort compares country names, not codes my @sorted = sort { $country_names{ $a } cmp $country_names{ $b } } map { substr( $_, 0, rindex( $_, '.' ) ) } @intl_files; foreach my $file ( @sorted ) { print "<option value=\"$file\">$country_names{$file}</option>\n"; } __DATA__ AL.txt DZ.txt AS.txt [download]	[reply] [d/l]
Re^2: hash sorting/alphabetization issue : country postal codes by hmbscully (Scribe) on Jul 03, 2007 at 20:06 UTC
Thank you. I understand the problem in my thinking now. I see that I needed to sort previous to the foreach loop rather than in it. I know there are always multiple ways to do things, but this one makes sense to me. I learn more and more about less and less until eventually I know everything about nothing.	[reply]
Re^3: hash sorting/alphabetization issue : country postal codes by ikegami (Patriarch) on Jul 04, 2007 at 03:32 UTC
I see that I needed to sort previous to the foreach loop rather than in it. No, that's not the problem you were having. And there's no problem with putting the `sort` inside the `foreach` statement. `my @codes = map { substr($_, 0, rindex($_, '.')) } @intl_files; foreach my $code ( sort { $country_names{$a} cmp $country_names{$b} } ) { print "<option value=\"$code\">$country_names{$code}</option>\n"; }` [download]	[reply] [d/l] [select]
Re: hash sorting/alphabetization issue : country postal codes by snopal (Pilgrim) on Jul 04, 2007 at 00:26 UTC
If you have arranged for the incoming data to be provided in your preferred order, you can retain that order in the HASH by using Tie::IxHash. This avoids the entire sort process. I don't know if this is more efficient than the sort process on this size list.	[reply]