[R] aggregate with cumsum

[Phil Spector]

Stephen -
    In version R-2.11.1, I get

> aggregate(myd[,c("val")],list(orig=myd$id1),cumsum)
   orig         x.1         x.2         x.3
1    a -0.62754524 -1.16194135 -0.05975811
2    b  0.21954618 -0.21355521 -0.62970082
3    c -0.30296239  1.44111610  0.30121880

Since myd has several observations for each value of orig,
you obviously can't just assign the output of aggregate
as a column of myd.

Were you thinking of

merge(myd,aggregate(myd[,c("val")],list(orig=myd$id1),cumsum))  ?

(Note that before version 2.11.1, aggregate *would* fail.))

 					- Phil Spector
 					 Statistical Computing Facility
 					 Department of Statistics
 					 UC Berkeley
 					 spector at stat.berkeley.edu


On Tue, 12 Oct 2010, Bond, Stephen wrote:

> Hello everybody,
>
> Data is
> myd <- data.frame(id1=rep(c("a","b","c"),each=3),id2=rep(1:3,3),val=rnorm(9))
>
> I want to get a cumulative sum over each of id1. trying aggregate does not work
>
> myd$pcum <- aggregate(myd[,c("val")],list(orig=myd$id1),cumsum)
>
> Please suggest a solution. In real the dataframe is huge so looping with for and subsetting is not a great idea (still doable, though).
> Thank you
>
>
> Stephen B
>
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>