[R] tabulating 2 factors weighting by a third var
Gerrit.Eichner at math.uni-giessen.de
Mon Dec 20 07:43:55 CET 2010
if V is you data frame, maybe
with( V, tapply( v3, list( v1, v2), sum))
does what you want.
Hth -- Gerrit
On Mon, 20 Dec 2010, Luca Meyer wrote:
> This must be an easy one but so far I haven't find a way out...
> I have a data frame such as:
> $ v1 : Factor w/ 5 levels
> $ v2 : Factor w/ 2 levels
> $ v3 : Class 'difftime' atomic [1:6666]
> basically v1 and v2 are factors, while v3 is a variable containing the
> duration of certain activities (values ranging from 11 to 45000 sec, no
> missing values)
> How can I get a table such that v1 levels will show as rows, v2 levels
> as columns and v3 is the weight by which table(v1,v2) is weighted? That
> is, instead of getting the count of occurences in each of the 10 cells
> of table(v1,v2) I would like to get the sum(v3), how can it be done?
> Luca Meyer
> IBM SPSS Statistics release 19.0.0
> R version 2.12.1 (2010-12-16)
> Mac OS X 10.6.5 (10H574) - kernel Darwin 10.5.0
> R-help at r-project.org mailing list
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
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