averaging rows on a data.frame according to a factor
On Nov 22, 2013, at 1:43 PM, john d wrote:
Dear all,
I apologize for the newbie question, but I'm stuck.
I have a data frame in the following form:
dat<-as.data.frame(cbind(c("a","a","a","b","b"), c(1,2,3,3,2),c(4,3,5,4,4)))
I need a way to generate a new dataframe with the average for each factor.
The result should look like:
Well, using the data,frame(cbind(...)) will ensure that you will NOT get factors, since cbind creates a matrix and that structure will not hold factors.
res<-as.data.frame(cbind(c("a","b"), c(2,2.5),c(4,4)))
Ouch.
Look at ?tapply or ?aggregate.
Perhaps:
dat<-data.frame(facts= c("a","a","a","b","b"), nums1=c(1,2,3,3,2),nums2=c(4,3,5,4,4))
aggregate(dat[-1], dat[1], mean)
Any help would be greatly appreciated. Jonathan [[alternative HTML version deleted]]
Newbie or not, you should still read the Posting Guide.
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
David Winsemius Alameda, CA, USA