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   • perl code blocks

     Top Answer

     Answered May 08, 2012 · 9 votes

     You didn't show the problematic code for some reason, but I think it's something like

     for my $val (@values) { sub sort_func { return $hash{$a}{$val} <=> $hash{$b}{$val}; }- my @newArr = sort sort_func @oldArr;}

     Not quite. The following only parses and compiles the sub once, yet it works:

     for my $val (@values) { my $cmp_func = sub { return $hash{$a}{$val} <=> $hash{$b}{$val}; };- my @newArr = sort $cmp_func @oldArr;}

     What matters is when what $val is captured. $val is captured when sub { ... } is evaluated. Keeping in mind that

     sub foo { ... }-

     is the same as the following in this regard,

     BEGIN { *foo = sub { ... }; }-

     In my code, it captures the $val from the foreach loop. In yours, it captures at compile time, so it captures the $val that existed at compile time. And that's not the variable you want.

     Now that you know how to make it work, you can move the complex code out of the way (out of the loop) as you desire.

     sub make_cmp_func { my ($hash, $val) = @_; return sub { return $hash->{$a}{$val} <=> $hash{$b}{$val}; };}for my $val (@values) { my $cmp_func = make_cmp_func(\%hash, $val); my @newArr = sort $cmp_func @oldArr;}

     Alternatively, you can pass the necessary values to the compare function instead of capturing them.

     sub cmp_func { my ($hash, $val, $a, $b) = @_; return $hash->{$a}{$val} <=> $hash{$b}{$val};}-for my $val (@values) { my @newArr = sort { cmp_func(\%hash, $val, $a, $b) } @oldArr;}

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     1/5

   • Perl Programming - How to match value of one column with another column in a given file

     Top Answer

     Answered Jul 17, 2019 · 1 votes

     perl -F'\t' -lane'print $F[10], "\t", $F[7]-$F[6]' \ < Alu.txt > Alu_lengthsubfam.csv-

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     2/5

   • Perl code for reverse complement of DNA sequence

     Top Answer

     Answered Apr 26, 2021 · 2 votes

     You only print the lines that contained a A, T, G or C. You want to print every line, so the print shouldn't be conditional.

     #!/usr/local/perl-use strict; # Alwaysuse warnings; # Alwayswhile (<>) { if (/^>/) { # Only modify lines starting with ">". tr/ATGC/TACG/; $_ = reverse($_); # You didn't reverse. } print; # Print undconditionally.}

     (tr/// and print use $_ by default.)

     Note I didn't open the file. You can use the program as follows:

     perl program.pl sequence02C.fna >sequence02C_revcomp.fna-

     or

     perl -i~ program.pl sequence02C.fna-

     The latter modifies the file in place. (Be careful! Test it first. It does make a backup, though.)

     Check all answers on Stack Overflow

     3/5

   • perl code for counting number of words in text file

     Top Answer

     Answered Jul 15, 2014 · 0 votes

     #!/usr/bin/perl-sub linux_style_count { $filename = shift; $lines = `wc -l < $filename`; $words = `wc -w < $filename`; $chars = `wc -c < $filename`; print "\nFile $filename contains"; print "\nNumber of Lines = $lines"; print "Number of Words = $words"; print "Number of Chars = $chars\n";}sub perl_style_count { $filename = shift; open(FILE, "<$filename") or die "Could not open file: $!"; my ($lines, $words, $chars) = (0,0,0); while (<FILE>) { $lines++; $chars += length($_); $words += scalar(split(/\s+/, $_)); } print "\nFile $filename contains"; print "\nNumber of Lines = " . $lines; print "\nNumber of Words = " . $words; print "\nNumber of Chars = " . $chars . "\n";}@files = <*>;foreach $file (@files) { if (-f $file) { &linux_style_count($file); &perl_style_count($file); }}

     OUTPUT

     [root@localhost /]# perl count.pl-File mytext.txt containsNumber of Lines = 9Number of Words = 22Number of Chars = 214File mytext.txt containsNumber of Lines = 9Number of Words = 22Number of Chars = 214File hello.txt containsNumber of Lines = 41Number of Words = 127Number of Chars = 888File hello.txt containsNumber of Lines = 41Number of Words = 127Number of Chars = 888File config.ini containsNumber of Lines = 32Number of Words = 58Number of Chars = 538File config.ini containsNumber of Lines = 32Number of Words = 58Number of Chars = 538

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     4/5

   • Perl code to serialize and deserialize variable like python pickle

     Top Answer

     Answered Mar 22, 2012 · 4 votes

     Untested.

     use Python::Serialise::Pickle qw( );-# Work around P::S::Pickle 0.01's extremely limiting interface.sub pickle_dumps { open(my $fh, '>', \my $s) or die $!; my $pickle = bless({ _fh => $fh }, 'Python::Serialise::Pickle'); $pickle->dump($_[0]); $pickle->close(); return $s;}my $data = [ "somestring.data", [ 178346464, 1234568 ] ];my $message = pack("N/a*", pickle_dumps($data));

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     5/5

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2. www.perl.orgThe Perl Programming Language - www.perl.org

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   The Perl Programming Language at Perl.org. Links and other helpful resources for new and experienced Perl programmers.

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3. www.geeksforgeeks.org › perl-programming-languagePerl Programming Language - GeeksforGeeks

   www.geeksforgeeks.org › perl-programming-language

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   Sep 26, 2023 · Last Updated : 26 Sep, 2023. Perl is a general purpose, high level interpreted and dynamic programming language. Perl supports both the procedural and Object-Oriented programming. Perl is a lot similar to C syntactically and is easy for the users who have knowledge of C, C++.

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5. en.wikipedia.org › wiki › PerlPerl - Wikipedia

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6. www.geeksforgeeks.org › perl-tutorial-learn-perlPerl Tutorial - Learn Perl With Examples - GeeksforGeeks

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