'grouping' matches?

[ktsirig]

Hi all!

I have a string :

$seq="IIIIIMMMMMMMMMMMOOOOOOOOOOOOOOOOMMMMMMMMMMMMMIIIIIMMMMMMMMMOOOOOOOOOOOOOOMMMMMMMMMMMMMIIIMMMMMMMMMMMOOOOOOOOOOOOOOOMMMMMMMMMMMIIIIIIMMMMMMMMMMMMMOOOOOOOOOOOOOOOOOOOOOOOMMMMMMMIIIMMMMMMMMMOOOOOOOOOOOOOOOOOOOOOOOOOOOMMMMMMMIIIIMMMMMMMMMMMOOOOOOOOOOOOOOOOOOOOOMMMMMMMIIIMMMMMMMMMOOOOOOOOOOOOOOOOOOOOOOOOOMMMMMMMMMIIIMMMMMMMMMMMOOOOOOOOOOOOOOOOOMMMMMMMMI";

and I want to find all groups of MMMMMM. I don't want to find only every position in the string that has 'M',
i.e. pos6, pos7, pos8, pos9 etc but I want to have something like:

1st group : pos 7-15
2nd group : pos 23-34
3rd group : pos 45-55

etc

[perl_diver]

one very straight forward method could be:

my $seq = 'IIIIIMMMMMMMMMMMOOOO.....OOOOOOOOOOOOMMMMMMMMI'; 
my @seq = split(//,$seq); 
my $flag = 0; 
my $start = 0; 
my $end = 0; 
my $group = 0; 
for my $i (0..$#seq) { 
 if ($seq[$i] eq 'M' && $flag == 0) { ($flag,$start) = (1,$i+1) } 
 if ($seq[$i] ne 'M' && $flag == 1) { ($flag,$end) = (0,$i) } 
 if ($end > $start) { 
 $group++; 
push @results, "Group $group : pos $start-$end"; 
 ($start,$end) = (0,0); 
 } 
} 
print "$_<br />" for @results; 

where 'IIIIIMMMMMMMMMMMOOOO.....OOOOOOOOOOOOMMMMMMMMI' is the full string you posted

[perl_diver]

Note: I assumed the first character in the string is one instead of zero which is why I add one to $i to get the start positions.