Hi Louis, You could try this:
# find the index of the maximum value in each row of _data_, # disregarding the last column classified <- apply(data[,-(nclass+1)],1,which.max) ## or, if the maximum may be repeated: classified <- apply(data[,-(nclass+1)], 1, FUN = function(x) which(x == max(x))) # the variable _truth_ is just the last column of _data_ ? truth <- data[,nclass + 1] ?table z <- table(classified, truth) HTH Joe Joe Crombie Biosecurity and Information Sciences Bureau of Rural Science Canberra Australia e: [EMAIL PROTECTED] -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Louis Martin Sent: Friday, 21 December 2007 11:37 AM To: R-help@r-project.org Subject: [R] using apply to loop Hi, I am running the following loop, but it takes hours to run as n is big. Is there any way "apply" can be used? Thanks. ### Start nclass <- dim(data)[[2]] - 1 z <- matrix(0, ncol = nclass, nrow = nclass) n <- dim(data)[[1]] x <- c(1:nclass) # loop starts for(loop in 1:n) { r <- data[loop, 1:nclass] classified <- x[r == max(r)] truth <- data[loop, nclass + 1] z[classified, truth] <- z[classified, truth] + 1 } # loop ends --------------------------------- [[alternative HTML version deleted]] ______________________________________________ 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. ------IMPORTANT - This message has been issued by The Department of Agriculture, Fisheries and Forestry (DAFF). The information transmitted is for the use of the intended recipient only and may contain confidential and/or legally privileged material. It is your responsibility to check any attachments for viruses and defects before opening or sending them on. Any reproduction, publication, communication, re-transmission, disclosure, dissemination or other use of the information contained in this e-mail by persons or entities other than the intended recipient is prohibited. The taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited. If you have received this e-mail in error please notify the sender and delete all copies of this transmission together with any attachments. If you have received this e-mail as part of a valid mailing list and no longer want to receive a message such as this one advise the sender by return e-mail accordingly. Only e-mail correspondence which includes this footer, has been authorised by DAFF ------ ______________________________________________ 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.
