Matching - Quick Perl Question

Shell Programming and Scripting
1

Hi everyone

I have a quick perl matching question. I have the following file, and I want to use perl to search through the 2nd column and see if it finds any of the month names (e.g.: Jan, Feb, Mar, ... Dec).

Here's the file I'm trying to search, and here's the code I have so far. Any help would be super helpful! Thanks :slight_smile:

lu Aug 2006 -122.24 48.76
lu AuG 2006 -122.24 48.76
21 2 2006 -122.24 48.76
2A Jul 2008 -117.8617 34.7017
21 Ma2 2006 -112.24 48.76

#!/usr/bin/perl -w
#

use strict;
use warnings;

my $file = 'sample1.xyt';
open my $info, $file or die "Could not open $file: $!";


        my $x1 = $_;
        my @cols = split(" ", $x1);



	#Test: to see if col2 has values that match the following EXACTLY: Jan, Feb, Mar, Apr, Jun, Jul, Aug, Sep, Oct, Nov, Dec AND ALSO check that there are no numbers in this column. If these criteria is not met, print the bad line

        if ($cols[1] =~ /^[0-9]+$/) {   #checks for all numbers in the month
                print "I have a bad month here - $x1";
        
        } elsif ($cols[1] =~ /^[a-zA-Z]+$/) {   #checks for all letters

                #check in here for matches!
                @months = ("Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"); 

                ##Not sure what to do here! :-(


                } else {
                        print "I have a bad month here - $x1";

                } 

        

        } else {
                print "I have a bad month here - $x1";

        }


}
close $info;
2

Try something like this which uses the "smart match" to perform a "in list":

use strict;
use warnings;

my @months =  ( "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" );
my $file   =  'sample1.xyt';


open my $info, $file or die "Could not open $file: $!";
while ( <$info> ) {
  chomp;
  my @cols   =  split(" ");
  if ( $cols[1] ~~ @months ) {
    print "Valid month found: $cols[1]\n";
  } else {
    print "Invalid month found: $cols[1]\n";
  }
}

arrays - Perl: if ( element in list ) - Stack Overflow

3

How about this:

#!/usr/bin/perl -w
use strict;
use warnings;

my @months = ("Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec");
open FILE, "<sample1.xyt" or die "Could not open sample1.xyt";

foreach my $line (<FILE>) {
        my @cols = split(" ", $line);

        if ($cols[1] =~ /^[0-9]+$/) {   #checks for all numbers in the month
                print "I have a bad month (numbers) here - $cols[1]\n";
        } elsif (grep /^$cols[1]$/i, @months) {
                   print "Month is ok - $cols[1]\n";
        } else {
                print "I have a bad month here - $cols[1]\n";
        }
}
close(FILE);
4

Alternation is probably faster than array comparison.

#!/usr/bin/perl

use strict;
use warnings;

open (my $file, '<', 'sample1.xyt');
while (<$file>){
   @rec=split/\s+/,$_;
   if ($rec[1]=~/^(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)/){
      ...
   }
else{
      print "Dud month in record $.:\n\t$_";
}
5

even more simpler with regexp, no array

#!/usr/bin/perl

use strict;
use warnings;

open (my $file, '<', 'sample1.xyt');
while (<$file>){
   if ($_=~/.+\s+(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\s+.+/i){
    print "month found $1\n";
   }
else{
      print "Dud month in record $.:\t$_";
}
}
close $file;

$ ./test.pl 
month found Aug
month found AuG
Dud month in record 3:    21 2 2006 -122.24 48.76
month found Jul
Dud month in record 5:    21 Ma2 2006 -112.24 48.76
6

this was super useful and incredibly instructive... thanks guys! :slight_smile: