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MathGroup Archive 2007

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Custom sort a list of pairs

  • To: mathgroup at smc.vnet.net
  • Subject: [mg73633] Custom sort a list of pairs
  • From: planetmarshalluk at hotmail.com
  • Date: Fri, 23 Feb 2007 04:41:55 -0500 (EST)

Hi there,

I've searched through existing posts to no avail, what I want to do is
this:
Sort a nested list of pairs, so that each pair is sorted by reverse
canonical order on its first element, and in normal order on its
second element.

For example, I want some function

sortPairs[items_]

that when given the input

{{ 1,a},{2,a},{3,a},{1,b},{2,b},{1,c}}

produces the output

{{3,a},{2,a},{2,b}{1,a},{1,b},{1,c}}

Any help much appreciated.

Thanks,
Andrew



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