Using indexing and putting a minus sign in front of a vector of column
names that you want to exclude would be a typical approach:
df <- data.frame(a=LETTERS[1:4], b= rnorm(4), c=rnorm(4), d=
letters[5:9])
apply(df[ , -c("a","d")], 2, sum)
(Pretty sure this will run properly but don't have R up an runnign to
test it.)
--
David Winsemius
On Jan 8, 2009, at 5:52 AM, Christian Kamenik wrote:
Dear all,
'Apply' is a great thing for running functions on rows or columns of
a matrix:
X <- rnorm(20, mean = 0, sd = 1)
dim(X) <- c(5,4)
apply(X,2,sum)
Is there a way to use apply for excluding rows or columns from a
matrix to run functions on the remaining rows or columns? I know, I
could do this with a 'for' loop, but 'apply' would be much easier
and quicker, and require less programming...
Cheers, Christian
______________________________________________
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.
