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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

• Follow-Ups:
  • Re: Custom sort a list of pairs
    • From: János <janos.lobb@yale.edu>