I have come up with this. I dont know whether using $& is effecient or not. 

use strict;
use warnings;
my $seq="IIIIIMMMMMMMMMMMOOOOOOOOOOOOOOOOMMMMMMMMMMMMMIIIIIMMMMMMMMMOO
+OOO
+OOOOOOOOOMMMMMMMMMMMMMIIIMMMMMMMMMMMOOOOOOOOOOOOOOOMMMMMMMMMMMIIIIIIM
+MMMMMMMMMMMMOOOOOOOOOOOOOOOOOOOOOOOMMMMMMMIIIMMMMMMMMMOOOOOOOOOOOOOOO
+OOOOOOOOOOOOMMMMMMMIIIIMMMMMMMMMMMOOOOOOOOOOOOOOOOOOOOOMMMMMMMIIIMMMM
+MMMMMOOOOOOOOOOOOOOOOOOOOOOOOOMMMMMMMMMIIIMMMMMMMMMMMOOOOOOOOOOOOOOOO
+OMMMMMMMMI";
while ($seq=~/(M+)/g)  {
    my $l = pos($seq);
    print $l-length($&)+1," to ",$l,$/;
}

[download]

Regards,
Murugesan Kandasamy
use perl for(;;);

In reply to Re: 'grouping' substrings? by murugu
in thread 'grouping' substrings? by Anonymous Monk

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