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| From: | Jeremy Ardley |
| Subject: | Efficient unique/sum column(s) |
| Date: | Wed, 05 Feb 2014 15:13:07 +0800 |
| User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 |
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Hi, I have a matrix A with columns x,y,c. Pairs of x,y repeat often. My objective is to efficiently sum all values of c for each unique x,y pair and generate output matrix B with x,y,csum columns Any advice appreciated. --
Jeremy Ardley |
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