[R] aggregate / collapse big data frame efficiently

Wensui Liu
Wed, 26 Dec 2012 03:32:07 -0000

aggregate() is not efficient. try by().


On Tue, Dec 25, 2012 at 11:34 AM, Martin Batholdy
<batholdy@googlemail.com>wrote:

> Hi,
>
>
> I need to aggregate rows of a data.frame by computing the mean for rows
> with the same factor-level on one factor-variable;
>
> here is the sample code:
>
>
> x <- data.frame(rep(letters,2), rnorm(52), rnorm(52), rnorm(52))
>
> aggregate(x, list(x[,1]), mean)
>
>
> Now my problem is, that the actual data-set is much bigger (120 rows and
> approximately 100.000 columns) – and it takes very very long (actually at
> some point I just stopped it).
>
> Is there anything that can be done to make the aggregate routine more
> efficient?
> Or is there a different approach that would work faster?
>
>
> Thanks for any suggestions!
>
> ______________________________________________
> R-help@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.
>



--
=============================WenSui Liu
Credit Risk Manager, 53 Bancorp
wensui.liu@53.com
513-295-4370
=============================
	[[alternative HTML version deleted]]