sorting a data.frame by mean values of grouped data
Thanks Mark,
I see that I made an error in my original request for help. I got my
labels and groups mixed up (see below). Nonetheless, your code has been
a good pointer in the direction of a solution. I'll post it up when I
have it working.
Thanks again,
Stephen Barry.
I should have written it more like this:
Given data.frame:
Value Group Label
55 D Small
33 D Small
11 D Small
55 D Small
66 D Small
11 D Small
19 A Big
29 A Big
39 A Big
3 B Small
2 B Small
5 B Small
6 B Small
5 B Small
6 B Small
2 C Big
3 C Big
3 C Big
3 C Big
3 C Big
3 C Big
3 C Big
end up with:
Value Group Label
19 A Big
29 A Big
39 A Big
2 C Big
3 C Big
3 C Big
3 C Big
3 C Big
3 C Big
3 C Big
55 D Small
33 D Small
11 D Small
55 D Small
66 D Small
11 D Small
3 B Small
2 B Small
5 B Small
6 B Small
5 B Small
6 B Small
>
Mark W Kimpel wrote:
Stephen,
I am sure someone will have a more elegant solution, but the following
works. Mark
d.lst <- split(x = d, f = as.factor(d$Group), drop = FALSE)
d.lst.mn <- sapply(d.lst, FUN =
function(x){mean(as.numeric(as.character(x$Value)))})
o <- order(d.lst.mn, decreasing = TRUE)
d.lst.mn <- d.lst.mn[o]
e <- NULL
for (i in 1:length(d.lst.mn)){
if (i == 1){
e <- d[d$Group == names(d.lst.mn)[i],]
} else {
e <- rbind(e, d[as.character(d$Group) == names(d.lst.mn)[i],])
}
}
e
Mark W. Kimpel MD ** Neuroinformatics ** Dept. of Psychiatry
Indiana University School of Medicine
15032 Hunter Court, Westfield, IN 46074
(317) 490-5129 Work, & Mobile & VoiceMail
(317) 204-4202 Home (no voice mail please)
mwkimpel<at>gmail<dot>com
******************************************************************
sjbarry wrote:
Hi,
I have what I think is a fairly straightforward problem. I've looked
through the FAQ's and mailing lists but have been unable to identify
a solution, probably because I don't understand the language well
enough.
I have a set of data d, with 3 columns as shown,
I want to sort the data Group, mean(Value by Label). I know that this
can be done for one level, say Label, using factor() but I cannot see
how to extend that. I have included the code to create the data.frame
below and would greatly appreciate a solution or a link to a similar
problem that has already been solved in the mailing list.
Value Label Group
19 Big A
29 Big A
39 Big A
55 Small D
33 Small D
11 Small D
55 Small D
66 Small D
11 Small D
2 Big C
3 Big C
3 Big C
3 Big C
3 Big C
3 Big C
3 Big C
3 Small B
2 Small B
5 Small B
6 Small B
5 Small B
6 Small B
Value <- c(19,29,39,55,33,11,55,66,11,2,3,3,3,3,3,3,3,2,5,6,5,6)
Group <- c("A","A","A","D","D","D","D","D","D",
"C","C","C","C","C","C","C","B","B","B","B","B","B")
Label <- c("Big","Big","Big",
"Small","Small","Small","Small","Small","Small",
"Big","Big","Big","Big","Big","Big","Big",
"Small","Small","Small","Small","Small","Small")
d <- as.data.frame(cbind(Value, Label, Group))
Thanks
Stephen Barry
Stephen Barry School of Earth and Environmental Sciences University of Wollongong Northfields Ave. Wollongong, NSW. 2522 Australia