Creating reverse dictionary

fish496 has asked for the wisdom of the Perl Monks concerning the following question:

I have a list of some 30000 Swedish words. The words of 3 extra swedish alphabets ö , å, å I wish to create a backward dictionry (Alphabetical sort from the last letter of the word) so that all the words with similar suffixes are together. In order to achieve this i tried to convert all the words to their reverse using reverse function but the 3 extra alphabets are replaced with some other charecters

¥ - å
€Ã -ä
¶Ã - ö

this is my code to reverse the word. How do i convert the string to reverse without getting above mentioned characters my code to reverse is like this

#!/usr/bin/perl -w

# Reading protein sequence data from a file, take 3
# The filename of the file containing the protein sequence data
$filename = 'svensk.txt';
# First we have to "open" the file
open(FILE, $filename);
# Read the protein sequence data from the file, and storeit
# into the array variable @protein
@WORDS = <FILE>;
# Print the protein onto the screen
##print scalar (@protein);

foreach $str (@WORDS)
{

$str2 = reverse $str;
print $str2;
}



close PROTEINFILE;

exit;
[download]

2019-02-08 Athanasius added code and pre tags

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Re: Creating reverse dictionary by GrandFather (Saint) on Feb 08, 2019 at 01:53 UTC
Perl needs to know that you are dealing with Unicode characters. Consider: `#!/usr/bin/perl use strict; use warnings; use utf8; my $str = "ö123 å456 å789"; open my $inFileUTF, '<:utf8', \$str; my @lines = <$inFileUTF>; chomp @lines; @lines = map {scalar reverse} @lines; print "Using utf8\n"; print "$_\n" for @lines; open my $inFile, '<', \$str; @lines = <$inFile>; chomp @lines; @lines = map {scalar reverse} @lines; print "\nUsing default file I/O\n"; print "$_\n" for @lines;` [download] Prints: `Using utf8 321ö 654å 987å Using default file I/O 321¶Ã 654¥Ã 987¥Ã` [download] Note the use of both strict and warnings. Always use strictures. Note the use of three parameter open and lexical file handles (usual file checking omitted because of the string trick). The `\$str` syntax lets me open the string as though it were a file. Very useful here to provide the data in the same "file" as the script. See PerlIO for a description of the open custom layer options - the :utf8 bit. Optimising for fewest key strokes only makes sense transmitting to Pluto or beyond	[reply] [d/l] [select]
Re: Creating reverse dictionary by haukex (Archbishop) on Feb 08, 2019 at 07:19 UTC
As GrandFather said, the issue you describe definitely sounds like an encoding issue. In terms of sorting, you might be interested in Unicode::Collate: use warnings; use strict; use Unicode::Collate; use utf8; use open qw/:std :utf8/; my @words=('två','tvagit','ägg','agget','öga','ogallrad','Offerdal'); my @rev = map {scalar reverse} @words; my @sorted = Unicode::Collate->new->sort(@rev); print "$_\n" for @sorted; __END__ agö åvt darllago ggä ladreffO tegga tigavt	[reply]
Re: Creating reverse dictionary by hippo (Archbishop) on Feb 08, 2019 at 09:54 UTC
How to handle this will depend on both the character encoding of your input file and the character encoding of your output (in this case, the terminal). Once you know these you can use Encode to decode from your input and encode to your output. Now, here are a few supplementary questions for you: Why no strict? Why do your comments refer throughout to protein sequences when instead you are dealing with a Swedish dictionary? Why persist with bareword filehandles? This combined with the lack of strict means that you did not spot that you have opened FILE but attempted to close PROTEINFILE. If you can correct these and properly decode from and encode to the correct character encodings you should be all set. Good luck.	[reply]
Re: Creating reverse dictionary by NetWallah (Canon) on Feb 08, 2019 at 01:47 UTC
Not sure about the contents of your file, but this works for me : `g>perl -E "$x.= chr($_) for (148,133,134); say $x ;say scalar reverse +$x " öàå åàö` [download] As a computer, I find your faith in technology amusing.	[reply] [d/l]