merging content based on common columns of 2 files using grep

heidi has asked for the wisdom of the Perl Monks concerning the following question:

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Re: merging content based on common columns of 2 files using grep by citromatik (Curate) on May 06, 2009 at 11:49 UTC
First of all, you should `use strict;` and `use warnings;` if you want to learn Perl the easy way There are some errors in your code, some of them: `file1.txt` and `file2.txt` are literal strings, so you should put them in quotation marks After read a file, you should chomp the line/s read The syntax you are using for grep is not correct, you should be using `grep BLOCK LIST` Here is a working version of your program: `use strict; use warnings; open(FH1,"file1.txt"); open(FH2,"file2.txt"); my @array=<FH2>; chomp @array; while(my $var=<FH1>){ chomp $var; my ($first,$second)=split(/\s+/,$var); my @grepped= grep {/\Q$second\E/} @array; print "$first\t$grepped[0]\n"; }` [download] You should also consider using hashes to solve your problem Another alternative, if the script is only going to join both files and output the result (and you are in a Unix/Linux system, as it seems to be the case) is to use bash's `join` tool: `$ join -1 2 -2 1 file1.txt file2.txt` [download] citromatik	[reply] [d/l] [select]
Re^2: merging content based on common columns of 2 files using grep by heidi (Sexton) on May 06, 2009 at 15:04 UTC
thank u :)	[reply]
Re: merging content based on common columns of 2 files using grep by targetsmart (Curate) on May 06, 2009 at 11:07 UTC
what is the output you got?, what is the problem you faced?. UPDATE from the code you shown above, it won't work as you expected. because for every line(first column) in the file1 you are printing the only the second column match from file2. grep will give only the matched indexes in this case use hash instead iterate through the second file and load the splitted line into a hash like the first column as key and second column as value(provided your second file is not in huge size) then when you are iterating the first file, just check exists in the hash, if exists append the hash value as the third column during print hope this helps Vivek -- In accordance with the prarabdha of each, the One whose function it is to ordain makes each to act. What will not happen will never happen, whatever effort one may put forth. And what will happen will not fail to happen, however much one may seek to prevent it. This is certain. The part of wisdom therefore is to stay quiet.	[reply]
Re^2: merging content based on common columns of 2 files using grep by heidi (Sexton) on May 06, 2009 at 11:10 UTC
The output was giving only the second column of the first file as results :(	[reply]
Re^3: merging content based on common columns of 2 files using grep by Anonymous Monk on May 06, 2009 at 11:14 UTC
Copy+Paste is your friend, friend :)	[reply]
Re^4: merging content based on common columns of 2 files using grep by Bloodnok (Vicar) on May 06, 2009 at 11:49 UTC
Re: merging content based on common columns of 2 files using grep by planetscape (Chancellor) on May 07, 2009 at 03:29 UTC
Have a look at Corion's most excellent join - join two files according to a common key. Sounds like it will do exactly what you want. HTH, planetscape	[reply]
Re: merging content based on common columns of 2 files using grep by bichonfrise74 (Vicar) on May 06, 2009 at 21:43 UTC
Try this... #!/usr/bin/perl use strict; my %hash; my $raw_file_1 = <<FILE_1; file1: TST_01 sp\|123\|fts TST_02 sp\|3438\|rvs TST_03 sp\|2744\|rtp TST_04 sp\|0123\|not_here FILE_1 my $raw_file_2 = <<FILE_2; file2: sp\|123\|fts checked_proved sp\|3438\|rvs proven_right sp\|2744\|rtp un_proved sp\|0000\|bogus bogus FILE_2 open( my $file_1, "<", \$raw_file_1 ) or die "Couldn't open \$raw_file +_1\n"; while (<$file_1>) { next if /^file/; my ($val, $key) = split; $hash{$key} = $val; } open( my $file_2, "<", \$raw_file_2 ) or die "Couldn't open \$raw_file +_2\n"; while (<$file_2>) { next if /^file/; my ($key, $val) = split; print "$hash{$key}\t$key\t$val\n" if ( defined($hash{$key}) ); } [download]	[reply] [d/l]