From: Carlos <angus@...>
Date: 2004-10-07T21:44:12+09:00
Subject: Re: Index of multiple similar strings

[Milo Thurston <nospam@linacreschoolofdefence.org>, 2004-10-07 14.19 CEST]
> I'm trying to read through a file like this:
> http://www.genomics.ceh.ac.uk/~milo/example.html
> In order to count the number of N tracts and locate their
> positions. My code goes like this:
> 
> dust_seq = # file in url above
> nums = 0
> d.dust_seq.scan(/[N]+/) do |blah|
> 	nums += 1
> 	puts "Index #{d.dust_seq.index(blah.to_s)}"
> done
> puts "Num of Ns: #{nums}"
> 
> In the example, the index for the third of the N groups
> is reported as the same as the first, as it's small enough
> to fit within it. Is there any way around this?

(not tested):

nums = 0
idx = 0

while idx = dust_seq.index /N+/, idx
	nums += 1
	puts "Index #{idx}"
	idx = Regexp.last_match.end(0)+1
end
puts "Num of Ns: #{nums}"