Hi, May be this helps:
dat1<- read.table(text=" Subject Block Trial Feature1 Feature2 1 1 1 48 40 1 1 2 62 18 1 2 1 34 43 1 2 2 51 34 1 3 1 64 14 ",sep="",header=TRUE) res1<-do.call(rbind,lapply(split(dat1,dat1$Block),function(x) data.frame(unique(x[,1:2]),t(colMeans(x[,-c(1:3)]))))) res1 # Subject Block Feature1 Feature2 #1 1 1 55.0 29.0 #2 1 2 42.5 38.5 #3 1 3 64.0 14.0 #With multiple subjects: dat2<- read.table(text=" Subject Block Trial Feature1 Feature2 1 1 1 48 40 1 1 2 62 18 1 2 1 34 43 1 2 2 51 34 1 3 1 64 14 2 1 1 48 35 2 1 2 54 15 2 2 1 49 50 2 2 2 64 40 2 3 1 38 28 ",sep="",header=TRUE) res2<-do.call(rbind,lapply(split(dat2,list(dat2$Subject,dat2$Block)),function(x) data.frame(unique(x[,1:2]),t(colMeans(x[,-c(1:3)]))))) res2<-do.call(rbind,split(res2,res2$Subject)) res2 # Subject Block Feature1 Feature2 #1 1 1 55.0 29.0 #2 1 2 42.5 38.5 #3 1 3 64.0 14.0 #4 2 1 51.0 25.0 #5 2 2 56.5 45.0 #6 2 3 38.0 28.0 A.K. ----- Original Message ----- From: Johannes Brand <brandjohan...@gmx.de> To: r-help@r-project.org Cc: Sent: Thursday, February 21, 2013 12:02 PM Subject: [R] remove rows in data frame by average Dear all, I have a data frame, which looks like this: Subject | Block | Trial | Feature1 | Feature2 .... 1 | 1 | 1 | ... | ... 1 | 1 | 2 | ... | ... 1 | 2 | 1 | ... | ... 1 | 2 | 2 | ... | ... 1 | 3 | 1 | ... | ... ...| ...| ...| ... | ... Can I remove the "Trial" column by averaging all the rows and without using a "for loop"? At the end my data frame should look like this: Subject | Block | Feature1 | Feature2 .... 1 | 1 | ... | ... 1 | 2 | ... | ... 1 | 3 | ... | ... ...| ...| ... | ... Thank you a lot for your help. Best, Johannes [[alternative HTML version deleted]] ______________________________________________ R-help@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. ______________________________________________ R-help@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.
