On Aug 31, 2010, at 5:19 PM, Iain Martyn wrote:
Hi, I have what I think is a simple question/issue but I have unable
to find the answer for it either in the R-manual or by browsing the
web.
I would like to know if there is a "mode" function in R, such that
from a vector or matrix the function returns the most common value.
In other programs I use (such as Matlab) I can have for exampe a 3X3
matrix A, A=[1 2 3; 1 3 2; 3 3 2] and I can find the mode of the
rows so that mode(A[1:3,:]) returns a 1X3 matrix [1 3 2].
Matlab must use row major order? Otherwise you statement doesn't make
sense. (You are going to need to adjust to R's default column major
order, if that's the case.)
Is this possible in R as well? If not, how would one go about this?
Have you considered using names(), which.max() and table()?
A=matrix(c(1, 2, 3, 1, 3, 2, 3, 3, 2), 3 ,3, byrow=TRUE)
apply(A, 2, function(x) names(which.max(table(x)) ))
# [1] "1" "3" "2"
You cannot use just which.max(table(.)) since that would return the
counts. If you want the number, then you need to wrap as.numeric
around the whole mess.
--
David Winsemius, MD
West Hartford, CT
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