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How to count unique strings


 
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# 1  
Old 07-30-2009
How to count unique strings

How do I count the total number of unique strings from a file using Perl? Any help is appreciated..
# 2  
Old 07-30-2009
Assuming by unique you mean 100% unique, and things like case or white space are included in the uniqueness:

Code:
use strict;
use warnings;
my %unique;
open my $FH, '/path/to/your/file' or die "$!";
while(<$FH>) {
    chomp;#<-- remove this line if the record seperator should be incuded
    $unique{$_};
}
close $FH;
foreach my $line (keys %unique) {
     print "$line = $unique{$line}\n";
}

Next time some effort on your part to first try and solve your programming requirements would be nice to see.
# 3  
Old 07-30-2009
Definitely. Thanks a lot.
# 4  
Old 07-30-2009
I'm not sure what happened in the code I posted, but this line:

$unique{$_};


should be:

$unique{$_}++;

So it displays the count of each unique line
# 5  
Old 07-30-2009
yes, I got an error message "Useless use of hash element in void context ....filename...

Thanx.

---------- Post updated at 02:40 PM ---------- Previous update was at 02:20 PM ----------

I've made changes to the code to handle utf8 as :--


use encoding 'utf8';

my %unique;
# my $unique;
my $line;

open my $FH, "<:encoding(utf8)", "$ARGV[0]" or die "Can't open file $ARGV[0]: $!";

while(<$FH>) {
chomp;
$unique{$_}++;
}
close $FH;
foreach my $line (keys %unique) {
print "$line = $unique{$line}\n";
}


However, I am getting the message....

2 files to edit.

I don't know this.
# 6  
Old 07-30-2009
is the message coming from die or when you print the hash or something else? That sure is not any perl error or warning I have ever seen.
# 7  
Old 07-31-2009
Thanks a lot.
I worked.

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