[R] Table Help

[Sean Davis]

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