Re: Compare CSV files

if you are a) on *nix and b) just want the values in column 3 that are unique to file 1, it might be easier from the shell:

cut -f3 -d, <file1.csv | sort -u >file1.cut.sort
cut -f3 -d, <file2.csv | sort -u >file2.cut.sort
comm -23 file1.cut.sort file2.cut.sort
[download]

Otherwise, if your requirements are more difficult, here is an example in Perl for the case of needing whole lines of file 1 in original order:

use strict;
use warnings;
my $file2 = {};
open my $fh2, "<file2.csv";
while( <$fh2> ) {
    chomp;
    my @fld = split /\,/;
    $file2 -> { $fld[2] } = 1;
}
close $fh2;
open my $fh1 "<file1.csv";
while( <$fh1> _ ) {
   chomp;
   my @fld = split /\,/;
   defined( $file2 -> { $fld[2] } ) and next;
   print "$_\n";
}
close $fh1;
[download]

-M

Free your mind

Comment on Re: Compare CSV files Select or Download Code

Replies are listed 'Best First'.
Re^2: Compare CSV files by Ovid (Cardinal) on Jul 19, 2006 at 16:00 UTC
Handy code, but it does suffer the problem that the commas might be quoted or that there are newlines in quotes (a common problem with hand-rolled CSV parsers). If the OPs CSV files are simple enough, then your code will be useful. Otherwise, he or she may be forced to find a way to sneak in modules (which is often much easier than it sounds). In any event, take my comments as caveats, not criticisms :) Your code has a good chance of working for simple CSV files. Cheers, Ovid New address of my CGI Course.	[reply]
Re^3: Compare CSV files by davorg (Chancellor) on Jul 19, 2006 at 16:07 UTC
he or she may be forced to find a way to sneak in modules Or, alternatively, try the standard Text::ParseWords module. I've never understood why that module isn't used more widely. -- <http://dave.org.uk> "The first rule of Perl club is you do not talk about Perl club." -- Chip Salzenberg	[reply]
Re^3: Compare CSV files by Moron (Curate) on Jul 19, 2006 at 16:07 UTC
Very true. I think I once wrote a simple Split routine that walks through strings willy-nilly where I was in a "no module" situation like the OP combined with applicability of the caveat you describe. -M Free your mind	[reply]