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Udo Stenzel wrote:
<blockquote cite="mid20061023213900.GA14959@web.de" type="cite">
<pre wrap="">jim burton wrote:
</pre>
<blockquote type="cite">
<pre wrap="">I want to split a string into 5 parts of equal length, with the last fifth
padded if necessary, but can't get it right - here's what I've got -
</pre>
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<pre wrap=""><!---->
fifths s = unwords.take 5.unfoldr (Just . splitAt l) $ s ++ repeat ' '
where l = (length s + 4) `div` 5
</pre>
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<br>
<br>
Okay, you win. That's the nicest answer so far, I think.<br>
<br>
But here are solutions with a different theme altogether. They are
based on groupBy, not unfoldr. I really like the new `on` function.<br>
<br>
<br>
module Chunk where<br>
<br>
import Data.List<br>
<br>
(on) f g = \x y -> f (g x) (g y)<br>
<br>
groupByIndex test xs =<br>
map (map snd) $ groupBy (test `on` fst) $ zip [0..] xs<br>
<br>
-- chunk : divide the input string into n chunks of equal length (len),
with padding<br>
<br>
-- chunk1 accepts the number of chunks<br>
chunk1 n pad xs = <br>
unwords $ take n $ groupByIndex ((==) `on` (`div` len)) $ xs ++
repeat pad<br>
where len = (length xs + n - 1) `div` n<br>
<br>
-- chunk2 accepts the length of each chunk<br>
chunk2 len pad xs = <br>
unwords $ take n $ groupByIndex ((==) `on` (`div` len)) $ xs ++
repeat pad<br>
where n = (length xs + len - 1) `div` len<br>
<br>
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