[R] averaging rows on a data.frame according to a factor

[Rui Barradas]

Sorry, there's a bug in my previous answer.

dat <- data.frame(c("a","a","a","b","b"), c(1,2,3,3,2), c(4,3,5,4,4))

aggregate(as.matrix(dat[,-1]) ~ dat[,1], FUN = mean)


Don't use as.data.frame(cbind(...)), everything becomes factors.

Rui Barradas

Em 22-11-2013 23:02, Rui Barradas escreveu:
> Hello,
>
> Try the following.
>
> aggregate(cbind(V2, V3) ~ V1, dat, FUN = mean)
>
>
> Hope this helps,
>
> Rui Barradas
>
> Em 22-11-2013 21:43, john d escreveu:
>> 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:
>>
>> res<-as.data.frame(cbind(c("a","b"), c(2,2.5),c(4,4)))
>>
>> Any help would be greatly appreciated.
>>
>> Jonathan
>>
>>     [[alternative HTML version deleted]]
>>
>> ______________________________________________
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>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
> ______________________________________________
> R-help at 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.