Re: how to change this code into perl

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Re^2: how to change this code into perl by Laurent_R (Canon) on Aug 30, 2015 at 07:55 UTC
I am afraid this: `perl -anle"next unless @L; print if $L[0] eq $F[0]; @L = @F;" in.txt > + out.txt` [download] will never enter into the loop because the `next` statement at the beginning will prevent @L from ever being set. Perhaps this instead: `perl -anwle 'BEGIN{$L = "";} print if $F[0] eq $L; $L = $F[0];' in.tx +t > out.txt` [download] Although the BEGIN block isn't really necessary if the warnings are not activated: `perl -anle 'print if $F[0] eq $L; $L = $F[0];' in.txt > out.txt` [download]	[reply] [d/l] [select]
Re^3: how to change this code into perl by BrowserUk (Patriarch) on Aug 30, 2015 at 08:14 UTC
You're right. I tried to type a pattern I've used before, directly into the browser without having had my morning coffee. It should be: `perl -anle"@L = @F, next if $. == 1; print if $L[0] eq $F[0]; @L = @F; +" in.txt > out.txt` [download] With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". I knew I was on the right track :) In the absence of evidence, opinion is indistinguishable from prejudice. I'm with torvalds on this Agile (and TDD) debunked I told'em LLVM was the way to go. But did they listen!	[reply] [d/l]
Re^4: how to change this code into perl by perlnewbie012215 (Novice) on Aug 30, 2015 at 16:40 UTC
thank you BrowserUK, I am getting this error. `syntax error at -e line 2, at EOF Execution of -e aborted due to compilation errors.` [download] I am pretty new to perl, what does the error mean. I googled but its not very clear	[reply] [d/l]
Re^5: how to change this code into perl by BrowserUk (Patriarch) on Aug 30, 2015 at 16:58 UTC
Re^3: how to change this code into perl by perlnewbie012215 (Novice) on Aug 30, 2015 at 16:34 UTC
Thank you Laurent_R!!! the one liner is not printing all the lines, say I have three duplicates its only printing the last two or one duplicate, not all of them. `1 twenty 2 thirty 1 forty 1 fifty` [download] `output 1 twenty 1 forty 1 fifty` [download] is there a way to script it instead of a oneliner. Thank you guys	[reply] [d/l] [select]
Re^4: how to change this code into perl by Laurent_R (Canon) on Aug 30, 2015 at 17:57 UTC
OK, a real script that should detect all lines having duplicate keys (quick script, untested, no time now, but based on something I am doing quite often, so, hopefully, I've it right). `my ($previous_key, $previous_line); open my $IN, "<", $infile or die "cannot open $infile $!"; while (<$IN>) { my $key = $1 if /^(\w+)/; if ($key eq $previous_key) { print $previous_line if defined $previous_line; print $_; undef $previous_line; } else { $previous_line = $_; } $previous_key = $key; }` [download]	[reply] [d/l]
Re^4: how to change this code into perl by Laurent_R (Canon) on Aug 30, 2015 at 17:42 UTC
Sure, where there are two entries with the same key, it only prints the second one (the duplicate, not the original one); when there are three, it will print only the second one and the third one. And of course, it will work only if the lines are properly sorted. If you need to print all the lines that are duplicates, then it is slightly more complicated, because you need to keep track of recent history. And then, yes, it is probably better to write a real script. Another way is to use a hash to keep track of everything in memory.	[reply]
Re^4: how to change this code into perl by perlnewbie012215 (Novice) on Aug 30, 2015 at 17:29 UTC
the file will be around 20000 rows and the first columns will always be text..	[reply]
Re^5: how to change this code into perl by poj (Abbot) on Aug 30, 2015 at 17:44 UTC
Re^4: how to change this code into perl by perlnewbie012215 (Novice) on Aug 30, 2015 at 19:07 UTC
Hi poj, thank you for the quick response, I tried the script and could not get the duplicate rows, the outcome came up with zero rows. below is the script i tried `open IN,'<','/home/scripts/imageoutcome.txt' or die "Could not open $i +nfile : $!"; my %count = (); my @lines = (); while (<IN>){ push @lines,$_; # print $_; if (/^(\S+)/){ ++$count{$1}; } } close IN; open OUT,'>','/home/scripts/outcome.txt' or die "Could not open $outfi +le : $!"; #print @lines; for (@lines){ if (/^(\S+)/){ print $count{$1}; print OUT $_ if $count{$1} > 0; } } close OUT;` [download]	[reply] [d/l]
Re^5: how to change this code into perl by poj (Abbot) on Aug 30, 2015 at 19:15 UTC
Re^6: how to change this code into perl by perlnewbie012215 (Novice) on Aug 30, 2015 at 20:16 UTC
Re^4: how to change this code into perl by poj (Abbot) on Aug 30, 2015 at 17:23 UTC
How big are the files and is the first column always numeric ? poj	[reply]
Re^4: how to change this code into perl by perlnewbie012215 (Novice) on Aug 30, 2015 at 19:14 UTC
Thank you very much Laurent_R, I tried the script and its printing all the rows, instead of duplicates. Laurent_R, this code looks very interesting, can you please explain it `#!/usr/bin/perl my ($previous_key, $previous_line); open my $IN, "<", '/home/scripts/imageoutcome.txt' or die "cannot open + $infile $!"; while (<$IN>) { my $key = $1 if /^(\w+)/; if ($key eq $previous_key) { print $previous_line if defined $previous_line; print $_; undef $previous_line; } else { $previous_line = $_; } $previous_key = $key; }` [download]	[reply] [d/l]
Re^5: how to change this code into perl by Laurent_R (Canon) on Aug 31, 2015 at 10:47 UTC
Re^4: how to change this code into perl by perlnewbie012215 (Novice) on Aug 30, 2015 at 19:40 UTC
Hi poj, you are correct, I forgot chomp, its working now. thank you so much for helping me.	[reply]
Re^4: how to change this code into perl by perlnewbie012215 (Novice) on Sep 01, 2015 at 22:39 UTC
Hi Laurent_R, That was my bad, I had hidden characters in it, thats why I did not work. Your script is working...thank you so much for helping me and explaining it..	[reply]