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Sparse Array Question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg130578] Sparse Array Question
  • From: christopher arthur <chris.arthur1 at gmail.com>
  • Date: Tue, 23 Apr 2013 00:04:24 -0400 (EDT)
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  • Reply-to: chris.arthur1 at gmail.com

Hello,

I have a list of rules for defining a SparseArray.  The list has some 
coordinates repeated with different values.  If a coordinate appears in 
the list more than once, I want to sum up the values, and then have a 
SparseArray

i.e., if my list were myList={{1,1}->1,{2,1}->2,{1,1}->3} then my 
SparseArray should have {1,1}->4.  I've tried using ReplacePart on an 
array to say myArray=ReplacePart[myArray,...] but this seems horribly 
inefficient as a way to change values in an array.

I'm using Mathematica 5.2

Cheers,

Chris



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