Hello,
Apart from the output order this does it.
(I have changed 'df' to 'df1', 'df' is an R function, the F distribution
density.)
df1 <- read.table(text="
PGID PTID Year Visit Count
6755 53121 2009 1 0
6755 53121 2009 2 0
6755 53121 2009 3 0
6755 53122 2008 1 0
6755 53122 2008 2 0
6755 53122 2008 3 1
6755 53122 2009 1 0
6755 53122 2009 2 1
6755 53122 2009 3 2", header=TRUE)
df2 <- with(df1, sapply(split(df1, list(PTID, Year)),
function(x) if (nrow(x)) x[which.max(x$Count), ]))
df2 <- do.call(rbind, df2)
rownames(df2) <- 1:nrow(df2)
df2
which.max(9, not which().
Hope this helps,
Rui Barradas
Em 25-07-2012 18:10, kborgmann escreveu:
Hi,
I have a dataset in which I would like to select rows based on matching
conditions and return the maximum value of a variable else return one row if
duplicate counts exist. My dataset looks like this:
PGID PTID Year Visit Count
6755 53121 2009 1 0
6755 53121 2009 2 0
6755 53121 2009 3 0
6755 53122 2008 1 0
6755 53122 2008 2 0
6755 53122 2008 3 1
6755 53122 2009 1 0
6755 53122 2009 2 1
6755 53122 2009 3 2
I would like to select rows if PTID and Year match and return the maximum
count else return one row if counts are the same, such that I get this
output
PGID PTID Year Visit Count
6755 53121 2009 1 0
6755 53122 2008 3 1
6755 53122 2009 3 2
I tried the following code and the output is almost correct but duplicate
values were included
df2<-with(df, sapply(split(df, list(PTID, Year)),
function(x) if (nrow(x)) x[which(x$Count==max(x$Count)),]))
df<-do.call(rbind,df)
rownames(df)<-1:nrow(df)
Any suggestions?
Thanks much for your responses!
--
View this message in context:
http://r.789695.n4.nabble.com/Select-rows-based-on-matching-conditions-and-logical-operators-tp4637809.html
Sent from the R help mailing list archive at Nabble.com.
______________________________________________
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.
