[R] output by(...)

Gabor Grothendieck ggrothendieck at gmail.com
Sun Mar 25 12:27:33 CEST 2012

2012/3/25 Skála, Zdeněk (INCOMA GfK) <Zdenek.Skala at gfk.com>:
> Dear all,
> I have a question that is probably pretty stupid, so apologies in advance...
> I do a simple
>> mydata.tab <- by(my.data.frame, my.data.frame$category, colMeans)
> ...works fine, but I need to output the results to some "flat" file (kind of table) to work with it in Excel etc.
> So I am doing now
>> capture.output(data.frame(unlist(mydata.tab)), file="mydata.txt")
> ...and process the result in Excel.
> Do you know a more pretty way to do this task? Perhaps something other than 'by()' to make a table of colMeans?

Try this:

do.call("rbind", by(iris[-5], iris[[5]], colMeans))

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email: ggrothendieck at gmail.com

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