count consecutive characters

Boetsie has asked for the wisdom of the Perl Monks concerning the following question:

Dear monks,

i have some large strings with character 'N' within it, the patterns are like;

xxxxxxxNNNNNxxxxxNxxxxNNNNNNNNxxx

xxNxxxNNNNNNNNNxxxxxx

etc...

For each string, i want the number of consecutive N's. So for the first string I want the numbers 5, 1 and 8. The second string I want the numbers 1 and 9.

Anyone knows how to do this?

Cheers, Marten

Comment on count consecutive characters

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Re: count consecutive characters by moritz (Cardinal) on Jun 07, 2010 at 08:38 UTC
Untested: `while ($str =~ /(N+)/g) { print length($1), "\n"; }` [download] See perlretut and maybe perlre for an explanation. (Updated after reading the question more carefully this time)	[reply] [d/l]
Re: count consecutive characters by johngg (Canon) on Jun 07, 2010 at 09:28 UTC
A similar approach to moritz's but using a map instead of a `while` loop to take advantage of the default behaviour of length to operate on `$_`. `$ perl -E ' > @strs = qw{ > xxxxxxxNNNNNxxxxxNxxxxNNNNNNNNxxx > xxNxxxNNNNNNNNNxxxxxx > }; > foreach $str ( @strs ) > { > print qq{$str : }; > say join q{, }, > map length, $str =~ m{(N+)}g; > }' xxxxxxxNNNNNxxxxxNxxxxNNNNNNNNxxx : 5, 1, 8 xxNxxxNNNNNNNNNxxxxxx : 1, 9 $` [download] I hope this is useful. Cheers, JohnGG Update: Changed second `print` statement to a `say` and got rid of the `say` with no arguments. What was I thinking?	[reply] [d/l] [select]
Re: count consecutive characters by Boetsie (Sexton) on Jun 07, 2010 at 09:54 UTC
Thanks both for replies, i've implemented Moritz method since it worked :) Thank you!	[reply]