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Re: Can you help me with these one-liners?

by BrowserUk (Pope)
on Apr 22, 2014 at 15:20 UTC ( #1083190=note: print w/replies, xml ) Need Help??

in reply to Can you help me with these one-liners?

Example1: perl -e 'while(<>) {if($_=~/^>/) {print $_;} else {$_=~tr/ATCG/TAGC/; +print $_;}}' FILE

Use -n to replace the while loop:

perl -nle 'if($_=~/^>/) {print $_;} else {$_=~tr/ATCG/TAGC/; print $_; +}' FILE

Do away with the unnecessary explicit references to $_:

perl -nle 'if(/^>/) {print;} else { tr/ATCG/TAGC/; print; }' FILE

Recognise that every line is being printed, so -p can replace the explicit print statements:

perl -ple 'if(/^>/) { ; } else { tr/ATCG/TAGC/; }' FILE

Rearrange to do away with the empty if body:

perl -ple 'tr/ATCG/TAGC/ unless( /^>/ );' FILE

UPDATE: a final step:

perl -ple '/^>/ or tr/ATCG/TAGC/' FILE

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