Hope I've got the techno details and the "protocol" right here.
I replied to your repy on my main thread as below. Appreciate if you could elucidate (love that word!) the regexp as per my words below. Various explorations with variants on ?<= give me the protein string split on the KR characters, with or without null strings, strings of just K or R, strings where consective K/R were condensed to just one, or none. I'm sure I can work it out with about 5 hours of exploration, but if you could just put into words what the ?<= is doibg I'd ber grateful.
I think should withdraw my words that there's nothing to be gained from the special functions when you're just marching down strings and doing a seemingly arbitrary logic function (and also my words about inadequate context). Splitting at simple marker points and counting a simple set of chars within the splits, combined with Perl's superb list handling, is not arbitrary spaghetti logic. Lesson learned.
One query: the ?<= construct was new to me, I've played with it and read up on it (perlre/Extended Patterns/Look-Around Assertions) and I'm 80% there but if anyone could explain exactly how this RE is ensuring I get exactly what I need I'd be grateful.Will continue to check some other posts, thanks all