Regular Expressions

Substitutions

To look for a pattern in the string and replace it with something else, use the following syntax: 
$string =~ s/PATTERN/REPLACEMENT_STRING/;

To do case-insensitive pattern matching, append an i to the substitution. 

$string =~ s/PATTERN/REPLACEMENT_STRING/i;

If you want the replacement to operate on all possible matches instead of just the first match, append a g to the substitution. 

$string =~ s/PATTERN/REPLACEMENT_STRING/g;
To remove all substrings matching the pattern write: 
$string =~ s/PATTERN//g;

Note that $string is changed after these operations!

Examples

# replace the first occurence of the word ID with "Identification";
$swiss_prot_line =~ s/ID/Identification/;


# replace all occurences of WIS with Weizmann Institute
$addresses =~ s/WIS/Weizmann Institute/g;

# remove all spaces, tabs etc. from a sequence entry
$seq =~ s/\s+//g;

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