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MathGroup Archive 2006

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RE: position lists

  • To: mathgroup at smc.vnet.net
  • Subject: [mg68697] RE: [mg68688] position lists
  • From: "David Park" <djmp at earthlink.net>
  • Date: Thu, 17 Aug 2006 04:17:56 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Igor,

What's the problem? It seems that all you have to do is Flatten the inner
lists.

a = {1, 1, 2, 2, 1, 4};

Flatten@Position[a, #1] & /@ Range[4]
{{1, 2, 5}, {3, 4}, {}, {6}}

I don't see much that is simpler.

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/

From: rych [mailto:rychphd at gmail.com]
To: mathgroup at smc.vnet.net


have
  In: a = {1, 1, 2, 2, 1, 4}
want
  {{1, 2, 5}, {3, 4}, {0}, {6}};

more effectively than just
  In: Position[a, #] & /@ Range[4]
  Out: {{{1}, {2}, {5}}, {{3}, {4}}, {}, {{6}}}

Ideas? Known one-liners?
Thanks
Igor



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