From: agemoagemo@...
Date: 2005-08-30T12:36:15+09:00
Subject: Re: [Q] how to unflatten a flat-array

--- Robert Klemme <bob.news@gmx.net> wrote:
> ?> %w{aa bb cc dd ee ff gg hh ii jj
> kk}.each_window(3) {|*a| p a}
> ["aa", "bb", "cc"]
> ["bb", "cc", "dd"]
> ["cc", "dd", "ee"]
> ["dd", "ee", "ff"]
> ["ee", "ff", "gg"]
> ["ff", "gg", "hh"]
> ["gg", "hh", "ii"]
> ["hh", "ii", "jj"]
> ["ii", "jj", "kk"]
> => ["aa", "bb", "cc", "dd", "ee", "ff", "gg", "hh",
> "ii", "jj", "kk"]

Am I the only one who thinks this seems a little
peculiar?

If I were writing something using this sort of 
functionality, I think I'd need and expect 
output something like:

[nil, "aa", "bb"]
["aa", "bb", "cc"]
["bb", "cc", "dd"]
["cc", "dd", "ee"]
["dd", "ee", "ff"]
["ee", "ff", "gg"]
["ff", "gg", "hh"]
["gg", "hh", "ii"]
["hh", "ii", "jj"]
["ii", "jj", "kk"]
["jj", "kk", nil]

Admittedly, it'd be hard to that reasonably with a
variable-size window of even length. But for a
previous-current-next arrangement, it seems to make
more sense to say "there is no previous" with a nil
than to basically skip the first item.

-Morgan


		
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