RE: [R] summing values by group

From: Ignacio Colonna <iacolonn_at_uiuc.edu>
Date: Fri 25 Mar 2005 - 05:00:21 EST


Maybe aggregate() is what you are looking for?

e.g. say your data frame is called 'mydata'

sum.by.CAT<-aggregate(mydata,list(CAT),sum)

this will give you sums by CAT for all the variables in the data set and will yield 'NA' for any character variables you may have.

Ignacio

-----Original Message-----
From: r-help-bounces@stat.math.ethz.ch
[mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of Larry White Sent: Thursday, March 24, 2005 10:12 AM
To: R-help@stat.math.ethz.ch
Subject: [R] summing values by group

At the risk of being wacked for asking what should be obvious....

I have a data frame with one categorical variable "CAT" and several numeric variables. I want to be able to get simple statistics on the numeric variables by level. For example, just as you can use table (CAT) to get the counts, I'd like to be able to get the means and sums by category.

If someone could point me in the right direction, I'd appreciate it. I've been through the SimpleR and Using R for Data Analysis... docs and I'm still clueless.

thanks for your help.



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R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Mar 25 05:10:54 2005

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