-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
Of arun
Sent: Thursday, February 21, 2013 1:45 PM
To: Johannes Brand
Cc: R help
Subject: Re: [R] remove rows in data frame by average
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 <brandjohannes at gmx.de>
To: r-help at 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
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