Hi, Might you replaced 'T' with a numeric value that signals the TRUE case without rumpling your matrix? 0 might be a good choice as it is never an index for a 1-based indexing system.
hold=apply(test,1,which.max) hold[apply(test,1,isUnique)==FALSE] <- 0 hold [1] 1 2 0 > On Mar 17, 2019, at 8:17 PM, Evan Cooch <[email protected]> wrote: > > Solved -- > > hold=apply(test,1,which.max) > hold[apply(test,1,isUnique)==FALSE] <- 'T' > > Now, all I need to do is figure out how to get <- 'T' from turning everything > in the matrix to a string. > > > On 3/17/2019 8:00 PM, Evan Cooch wrote: >> Got relatively close - below: >> >> On 3/17/2019 7:39 PM, Evan Cooch wrote: >>> Suppose I have the following sort of structure: >>> >>> test <- matrix(c(2,1,1,2,2,2),3,2,byrow=T) >>> >>> What I need to be able to do is (i) find the maximum value for each row, >>> (ii) find the column containing the max, but (iii) if the maximum value is >>> a tie (in this case, all numbers of the row are the same value), then I >>> want which.max (presumably, a tweaked version of what which.max does) to >>> reurn a T for the row where all values are the same. >>> >>> Parts (i) and (ii) seem easy enough: >>> >>> apply(test,1,max) --- gives me the maximum values >>> apply(test,1,which.max) --- gives me the column >>> >>> But, standard which.max doesn't handles ties/duplicates in a way that >>> serves my need. It defaults to returning the first column containing the >>> maximum value. >>> >>> What I'd like to end up with is, ultimately, something where >>> apply(test,1,which.max) yields 1,2,T (rather than 1,2,1). >>> >>> So, a function which does what which.max currently does if the elements of >>> the row differ, but which returns a T (or some such) if in fact the row >>> values are all the same. >>> >>> I've tried a bunch of things, to know avail. Closest I got was to use a >>> function to test for whether or not a vector >>> >>> isUnique <- function(vector){ >>> return(!any(duplicated(vector))) >>> } >>> >>> which returns TRUE if values of vector all unique. So >>> >>> apply(test,1,isUnique) >>> >>> returns >>> >>> [1] TRUE TRUE FALSE >>> >>> but I'm stuck beyond this. >> >> The following gets me pretty close, >> >> test_new <- test >> test_new[which(apply(test,1,isUnique)==FALSE),] <- 'T' >> >> but is clunky. >> >> >> >> >> >> > > ______________________________________________ > [email protected] mailing list -- To UNSUBSCRIBE and more, see > 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. Ben Tupper Bigelow Laboratory for Ocean Sciences 60 Bigelow Drive, P.O. Box 380 East Boothbay, Maine 04544 http://www.bigelow.org Ecological Forecasting: https://eco.bigelow.org/ ______________________________________________ [email protected] mailing list -- To UNSUBSCRIBE and more, see 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.
