It looks like the sentences in your file are not separated by new lines, or at least not by new lines recognized by the perl script. If you are on a Mac this can happen when you export files from Excel or Filemaker - the new lines are in the Classic Mac format (carriage return) rather than the Unix format (line feed). Try this to see: 
my $count = 0;
open($fh,"<",$sentence_file) or die "Could not open $sentence_file: $!
+";
while (my $sentence = <$fh>) {
    chomp $sentence;
    $count++;
    print "Sentence $count\n";
}
close($fh);

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If it only counts one sentence then this is your problem. If you use a text editor like BBEdit you can change the format of your files by opening Edit->Document Options and choosing Unix. Alternatively, you can set the line break that Perl sees at the top of your script (before opening the files): 
#!/usr/bin/perl
use warnings;
use Algorithm::NaiveBayes;

local $/ = "\015";

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In reply to Re^9: how to use Algorithm::NaiveBayes module by tangent
in thread how to use Algorithm::NaiveBayes module by agnes

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