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)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*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

**Follow-Ups**:**Re: Sparse Array Question***From:*Sseziwa Mukasa <mukasa@gmail.com>

**Re: Sparse Array Question***From:*Bob Hanlon <hanlonr357@gmail.com>

**Re: Sparse Array Question***From:*Bob Hanlon <hanlonr357@gmail.com>