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Re: programming comptition II

  • To: mathgroup at
  • Subject: [mg5047] Re: programming comptition II
  • From: rhall2 at (hall robert)
  • Date: Wed, 23 Oct 1996 01:38:10 -0400
  • Organization: University of Maryland, Baltimore County
  • Sender: owner-wri-mathgroup at

In article <54f397$74f at>, Xah Lee  <xah at> wrote:
>Problem Two: Pairing of Nodes.
>Given two list of the same Dimensions, how to combine the list so that
>the end nodes of the new list pair the end nodes of given lists. Example
>and solution:
>Clear[li1, li2]
>li1 = Array[f, {2,3,4}]
>li2 = Array[g, {2,3,4}]
>Transpose[ {li1, li2},
>RotateRight@ Range@ Length@ Dimensions@ {li1, li2}

Mathematica has built-in functions for dealing with multiple lists.
   MapThread[List, {li1, li2}, Depth[li1] -2]
Alternately, you can get around the fact that List[] isn't listable with
   ListableFunction[li1, li2] /. ListableFunction -> List
For example
   li1 + li2 /. Plus -> List
This won't work with numbers; the function will be evaluated at
the number pairs and each pair will be replaced by a single value.

Bob Hall            | "Know thyself? Absurd direction!
rhall2 at  |  Bubbles bear no introspection."  -Khushhal Khan Khatak

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