Message-ID: <1351803128.3246.YahooMailNeo@web142604.mail.bf1.yahoo.com>
Date: 2012-11-01T20:52:08Z
From: arun
Subject: Select the last rows of when specific conditions are met.
In-Reply-To: <1351783108971-4648133.post@n4.nabble.com>
HI,
Saw your response in Nabble.
Try this:
dat1<-read.table(text="
Subj Trial? tt?
1????????? 1????? 1???
1????????? 1????? 2???
1????????? 1????? 3???
1????????? 1????? 4????
1????????? 1????? 5????
1????????? 2????? 1????
1????????? 2????? 2????
1????????? 2????? 3????
1????????? 3????? 1????
1????????? 3????? 2????
1????????? 3????? 3????
2????????? 1????? 1????
2????????? 1????? 2????
2????????? 1????? 3
",sep="",header=TRUE)?
??
res<-do.call(rbind,lapply(split(dat1,list(dat1$Subj,dat1$Trial)),function(x) x[x[,3]<4,]))
?rownames(res)<-1:nrow(res)
?res
#?? Subj Trial tt
#1???? 1???? 1? 1
#2???? 1???? 1? 2
#3???? 1???? 1? 3
#4???? 2???? 1? 1
#5???? 2???? 1? 2
#6???? 2???? 1? 3
#7???? 1???? 2? 1
#8???? 1???? 2? 2
#9???? 1???? 2? 3
#10??? 1???? 3? 1
#11??? 1???? 3? 2
#12??? 1???? 3? 3
?A.K.
----- Original Message -----
From: mardijk <van_dijkmarianne at hotmail.com>
To: r-help at r-project.org
Cc:
Sent: Thursday, November 1, 2012 11:18 AM
Subject: [R] Select the last rows of when specific conditions are met.
Hello,
As I am new with R I am completely stuck in resolving a, no doubt, easy
problem.
I have a dataset with an enormous amount of rows and 17 columns. I need to
know per trial and subject number if another variable (tt) exceeds a
maximum. If this is true than the last 5000 rows of that specific trial for
that subject number needs to be deleted.
But I am completely stuck on how to do so. After various attempts I have
finally come up with the following (which obviously does not work).
if (dat["tt"]>6000
){
??? return(
??? tail(dattest[,c("Trial", "Subj" )],n=5000) <- NA
}
Can anybody explain what I need to do?
Thank you so much!
--
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