From: Joel VanderWerf <vjoel@...>
Date: 2007-04-29T03:34:07+09:00
Subject: Re: cyclic array

Xavier Noria wrote:
...
>   module Enumerable
>     def each_cycle(window, start=0)
>       (start...length+start).each do |i|
>         yield((i..i+window).map {|n| self[n % length]})
>       end
>     end
>   end

Here is a slight variation, for amusement, but it doesn't work for 
window > length:

   module Enumerable
     def each_cycle(window, start = 0)
       (-length+start...start).each do |i|
         yield values_at(*(i..i+window))
       end
     end
   end

   a = [ "a", "b", "c", "d", "e", "f", "g"]
   a.each_cycle(4) do |cycle|
     puts "#{cycle}"
   end

   a.each_cycle(14) do |cycle|
     puts "#{cycle}"
   end

__END__

abcde
bcdef
cdefg
defga
efgab
fgabc
gabcd

abcdefgabcdefg
bcdefgabcdefg
cdefgabcdefg
defgabcdefg
efgabcdefg
fgabcdefg
gabcdefg

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407