From: Sean Davis <sdavis2_at_mail.nih.gov>

Date: Thu 26 May 2005 - 01:43:25 EST

>

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Thu May 26 01:55:54 2005

Date: Thu 26 May 2005 - 01:43:25 EST

On May 25, 2005, at 9:35 AM, McMurtry, Benjamin G. wrote:

> I'm slightly confused with aggregate, will I need to loop it until it

*> stops
**> returning sub lists? Or would I somehow need to convert my username
**> column
**> into a unique list and then do FUN=sum??
*

Ben,

Generally, it is OK (and encouraged) to post back to the list, just so we all learn from each others' posts.

Here is an example:

> a <- data.frame(group=rep(letters[1:3],10),values=rnorm(30)) > a

group values 1 a -0.146140983 2 b 0.190071267 3 c 0.207708591 4 a -1.126531350 5 b -0.013761243 6 c -0.212028409 7 a 1.012215244 8 b -0.487072132 9 c 0.667999520 10 a 0.276094321 11 b 0.835611948 12 c -1.049264490 13 a 0.399050191 14 b -1.177174650 15 c -1.471944114 16 a -0.410480517 17 b 0.006008521 18 c 1.608219688 19 a -0.120729414 20 b 1.074361542 21 c 1.782826882 22 a 1.336191577 23 b 0.721519413 24 c -0.594837423 25 a 1.120628507 26 b -2.011601905 27 c -0.076464599 28 a -1.512376840 29 b 1.182703732 30 c -1.620904211 > aggregate(a[,2],by=list(a[,1]),sum) Group.1 x 1 a 0.8279207 2 b 0.3206665 3 c -0.7586886

>

Hope that helps.

Sean

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Thu May 26 01:55:54 2005

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