Quantified Regex Replacement

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

Hi,

I have a string with brackets inside it. Now, when a string has more than 1 bracket pairs I would like to: 1) Take away two consecutive closing and opening bracket, 2) Replacing the characters in between with "N" -- as many as the characters to be repaced. Here is the example

my $input_str1 = "TG[CCC]CC[TTT]";

# Desired result is this:

my $rep1 = "TG[CCCNNTTT]";  
# Two Ns replace two Cs in between ][.

# Similarly 
my $input_str2 = "TG[CCC][TTT]";
my $rep2 = "TG[CCCTTT]";
[download]

But when there are only 1 bracket pairs, I want to leave it intact:

my $input_str3 = "TG[CCAAATTT]";

# Desired result is this:

my $rep3 = "TG[CCAAATTT]";
[download]

I have this, but it doesn't work.

$str =~ s/\][ATCG]+\[/N/;
[download]

Is there a single regex stroke that can handle above situations?

Regards,
Edward

Comment on Quantified Regex Replacement Select or Download Code

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Re: Quantified Regex Replacement by japhy (Canon) on Feb 23, 2006 at 05:42 UTC
I'd suggest `s/\]([ATCG]+)\[/"N" x length($1)/e`, which replaces the `]...[` part with one "N" for each letter in between the closing and opening bracket. Jeff `japhy` Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and `perl` hacker How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart	[reply] [d/l] [select]
Re^2: Quantified Regex Replacement by Samy_rio (Vicar) on Feb 23, 2006 at 05:54 UTC
Hi, Try this, `while(<DATA>){ s/\]([ATCG])\[/'N' x length($1)/e; print $_; } __DATA__ TG[CCC]CC[TTT] TG[CCC][TTT] TG[CCAAATTT] Respective Output is: TG[CCCNNTTT] TG[CCCTTT] TG[CCAAATTT]` [download] Updated: monkfan, Try below code for your second question. `while(<DATA>){ s/\]([ATCG])\[/my $a = $1; $a =~ s![^C]+!'N' x length($1)!e; $a/e; print $_; } __DATA__ TG[CCC]CC[TTT] Respective Output is: TG[CCCCCTTT]` [download] Regards, Velusamy R. eval"print uc\"\\c$_\""for split'','j)@,/6%@0%2,`e@3!-9v2)/@\|6%,53!-9@2~j';	[reply] [d/l] [select]
Re^2: Quantified Regex Replacement by monkfan (Curate) on Feb 23, 2006 at 05:53 UTC
Thanks so much for your reply. I am just wondering how can I just take away the two consecutive reversed brackets -- ][. Like this: `my $str = "TGC[CCC]CC[TTT]"; # Into my $rep = "TG[CCCCCTTT]";` [download] Still my regex below doesn't do it right, it also removes two Cs in between: `$str =~ s/\]([ATCG]+)\[//;` [download] Regards, Edward	[reply] [d/l] [select]
Re^3: Quantified Regex Replacement by japhy (Canon) on Feb 23, 2006 at 14:48 UTC
That's because your substitution matches the `]...[` part and replaces it with nothing! You'll have to replace it with $1, which in your regex, contains the letters in between the closing and opening brackets. `s/\]([ACTG]+)\[/$1/` Jeff `japhy` Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and `perl` hacker How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart	[reply] [d/l] [select]