Thanks for your reply, but that is not quite what I am looking for...I do not want to add up all the values in the row, I want to get the number of columns in each row that meet the criteria and then get that as a percentage....
my understanding is that the rowSums function adds up the values does it not? I tried your code anyways and it did not work: Error in abs(pwdiff) >= t : comparison (5) is possible only for atomic and list types and when specifying the columns (perc[x]<-rowSums(pwdiff[,abs(pwdiff[x,])>=thr], na.rm=T)/ncol(pwdiff)), I get the following error: Error in rowSums(pwdiff[, abs(pwdiff[x, ]) >= thr], na.rm = T) : 'x' must be an array of at least two dimensions In addition: There were 30 warnings (use warnings() to see them) > warnings() Warning messages: 1: In perc[x] <- rowSums(pwdiff[, abs(pwdiff[x, ]) >= thr], ... : number of items to replace is not a multiple of replacement length ... Ive been trying to sort this out for the past three days and cannot get it to work for some reason...I can do it SO easily in excel with a simple macro, but doing that on a 480000x780 table inevitably crashes the computer... Any more help you can provide would be great, thanks! -- View this message in context: http://r.789695.n4.nabble.com/counting-columns-that-fulfill-specific-criteria-tp3622265p3622711.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.