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Re: Search and delete lines based on string matching

by imp (Priest)
on Mar 13, 2007 at 14:20 UTC ( #604536=note: print w/ replies, xml ) Need Help??


in reply to Search and delete lines based on string matching

In addition to davorg's advice above you should also always use both strict and warnings, as they can help you identify many common problems.

If you are searching for the words from file A in file B then you will need a different regex. The code you provided is using the entire file A as the regex.

Here's an example that uses one pattern file, one input file, one output file:

use strict; use warnings; if (@ARGV != 3) { print "Usage: $0 <pattern file> <input file> <output file>\n"; exit; } my ($pattern_filename, $source_filename, $dest_filename) = @ARGV; open my $pattern_fh, '<', $pattern_filename or die "Failed to open $pa +ttern_filename: $!"; my @tokens = (); while (my $line = <$pattern_fh>) { push @tokens, split /\s/, $line; } # Create a pattern with alternation of tokens, wrapped in a non-captur +ing group, # and a requires word break before and after the word to prevent match +ing pieces # of other words my $pattern = '\b(?:' . join('|', @tokens) . ')\b'; print "Search pattern: $pattern\n"; open my $infile, "<", $source_filename or die "Failed to open $source +_filename: $!"; open my $outfile,">>", $dest_filename or die "Failed to open $dest_f +ilename: $!"; while(my $line = <$infile>) { if ($line !~/$pattern/) { print "adding: $line"; print $outfile $line; } } close($infile); close($outfile);


Comment on Re: Search and delete lines based on string matching
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Re^2: Search and delete lines based on string matching
by brut (Initiate) on Mar 13, 2007 at 14:30 UTC
    Thanks a lot buddy... It did helped..
Re^2: Search and delete lines based on string matching
by brut (Initiate) on Mar 13, 2007 at 14:35 UTC
    Just adding to the above problem..Suppose in the same code I have to add instead of deleting the strings matched.. Like strings that are in A but not in B and I want to add them using some string like "This is new addition" before adding those strings to file B and writing out in C.
      How is your input data formatted?
      1. bin den mig
      2. bin
        den
        mig
      3. bin deg
        mig
        Its as in option 2..that is new line character after each string. I am facing a problem in the code you provided that it is not able to delete strings like bin[0] , bin 12 and bin234. Can you please help on this also.
        Its as in option 2 that is new line after every string in both A and B. Also in your code the strings like bin\5\ , bin \43\ and bin\123\ (like array elements with element number in square brackets)are not getting deleted from B. Can you help on this?
      As suggested above, What code have you tried?
      Here's an approach that initializes a hash of output tokens, prepopulated with marker text for new additions. The output data is overridden for existing entries, and a sorted list is appended to the specified output file (open with '>' instead of '>>' if you don't want this). Note that it isn't fully compatible with the delete code I posted earlier, since that code didn't take comments into account.
      #!/usr/local/bin/perl use strict; use warnings; if (@ARGV != 3) { print "Usage: $0 <pattern file> <input file> <output file>\n"; exit; } my ($pattern_filename, $source_filename, $dest_filename) = @ARGV; open my $pattern_fh, '<', $pattern_filename or die "Failed to open $pa +ttern_filename: $!"; my %output_tokens = (); while (my $line = <$pattern_fh>) { chomp $line; $output_tokens{$line} = "$line # Added by script"; } print "Expected tokens: ", join(', ', keys %output_tokens), "\n"; open my $infile, "<", $source_filename or die "Failed to open $source +_filename: $!"; open my $outfile,">>", $dest_filename or die "Failed to open $dest_f +ilename: $!"; while(my $line = <$infile>) { chomp $line; $output_tokens{$line} = $line; } for my $token (sort keys %output_tokens) { print $output_tokens{$token}, "\n"; } close($infile); close($outfile);
        Hey The very first code you provided me with is really working fine for no +rmal strings without any non-alphabet characters except for its not w +orking for strings which are like A[0] B[1] So please resolve this .. I tried using the fix you gave but its not w +orking.So need to modify the code for these cases of strings also. Rest everything is really fine. And real thanks for all the innovative solutions you have provided.You + really are excellent.

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