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longest sequence...

Posted on 2009-04-10
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Last Modified: 2012-05-06
I got the below code from expert-exchange for getting the longest sequence.... starts with atg and ends with any of 3 codens..

when i give one sequence as input it gives perfect answer ....

but when i give two sequence as inputs it's giving answer for only one sequence....

so what modifications should i do...


sample sequences:


>G7H5
AATATGATTTTGAATTTGGTTCAAAATGAAACCGTCTCCGTTCATTGTTTTGATATTTGCTGTTATTATAGGCCTGTGTGGTTGTGCACCACCCAAGGCCGAAGAAACTCAATCTGCTACGAGTACGAAAGCCGAGTCTTCTAATGCGGGTCAGAGCGGAAATCGATATCCACCGGTGAAGATGAATTTTGAAAAAGTGTTTACTCCTAGTTTTTGTAAAGGTTTGCAAGATCAGCAATCAAAAATTGAAGAACTTTCGGCAGACTTGGAGAGGTTTGAGGGTCAGGAATTGAAGTCAAATTATGGAACATATTCCGACAAAAAGGACCATAAATAAAAATTTGTCCAGCAAAAGATATGGTTGCATAATAAACGCAAATATAATCATACACGCCCAAAAAAAAAAAAAAAAAAAAAAAA

>G8C4
GGGAGTATAATCTTGAATTTGGTTCAAAATGAAACTGTCTCTGTTCATTATTTTTTTGATATTTGCTGTTATTATAGGCCTGTGTGGTTGTGCACCACCCAAGGCCGAAGGAACTAAATCTGGTATGGGAACGCAAGCCGAGTCTTCTAATGCGGGTCAGAGAGGAAGTCGAAACAATGGCATCTCATCGGCGGAGTTGAACTTTGACAGAATTTCTCCTGGTTTTATTAAAGGTTTGCGTGAAGATCAATCAGGATATGAAAAAGTTGGAGAGATCTTGAAGAGGGCTCAGGATCAGCAATTGAAGTCAAATTATGGAAAATATTCCGACAAAAAGGCCCATAATTAAAAATTTGTTCAGCAAAAAATTTGGTTGCATAATAAACCCAAAAATAATCATCCCCGCAAAAAAAAAAAAAAAAAAAAAAAAAA
#!/usr/bin/perl
use warnings;
use strict;
 
open INPUT,"<input.txt" or die $!;
my $name=<INPUT>;
local $/;
$_ = <INPUT>;
close INPUT;
s/\s+//g;
my $longest_str ='';
my $longest_len = 0;
open P,">possible.txt" or die $!;
while( /ATG(?=((?:...)*?(?:TAA|TAG|TGA)))/g ){
   print P "ATG$1\n";
    if( length $1 >$longest_len ){
        $longest_str=$1;
        $longest_len=length $1;
    }
}
close P;
open OUTPUT,">output.fasta" or die $!;
print OUTPUT $name,"ATG",$longest_str if $longest_len;
close OUTPUT

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Question by:shragi
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6 Comments
 
LVL 25

Accepted Solution

by:
lwadwell earned 500 total points
ID: 24120119
Hi shragi,

you will need to change the code to loop through the input file and process each "set" of sequences.  I have had an attempt at it below ... I think it does what you want.

lwadwell
#!/usr/bin/perl
use warnings;
use strict;
 
open INPUT,"<input.txt" or die $!;
open OUTPUT,">output.fasta" or die $!; 
my $name; 
while ( my $string = <INPUT> ) {
	chomp($string);            # remove trailing new lines
	$string =~ s/\s+//g;       # remove whitespace
	next if ( $string eq "" ); # start loop again if blank line
	if ( $string =~ /^>/ ) {   # if line starts with a '>', save as $name
		$name = $string;
		next;
	}
	my $longest_str ='';
	my $longest_len = 0;
	open P,">possible.txt" or die $!;
	while( $string =~ /ATG(?=((?:...)*?(?:TAA|TAG|TGA)))/g ){
   		print P "ATG$1\n";
    	if ( length $1 >$longest_len ){
        	$longest_str=$1;
        	$longest_len=length $1;
    	}
	}
	close P;
	print OUTPUT $name,"ATG",$longest_str,"\n" if $longest_len;
}
close INPUT;
close OUTPUT

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Author Comment

by:shragi
ID: 24128135
one small change required..

there is no space between name and sequence...
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Author Comment

by:shragi
ID: 24128136
I need a space between them...
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LVL 5

Expert Comment

by:vikaskhoria
ID: 24128310
Just change line 27 in the script above as:
(added space before and after ATG in quotes)
print OUTPUT $name," ATG ",$longest_str,"\n" if $longest_len;

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LVL 25

Expert Comment

by:lwadwell
ID: 24128492
If you don't want one after the ATG then use
print OUTPUT $name," ATG",$longest_str,"\n" if $longest_len;

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Author Closing Comment

by:shragi
ID: 31568994
Perfect..
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