Dear R users, I have a matrix of both negative and positive values that I would like to randomly sample with the following 2 conditions:
1. only sample positive values 2. once a cell in the matrix has been sampled the row and column of that cell cannot be sampled from again. #some dummy data set.seed(101) dataf <- matrix(rnorm(36,1,2), nrow=6) I can do this quite simply if all the values are positive by using the sample function without replacement on the column and row indices. samrow <- sample(6,replace=F) samcol <- sample(6,replace=F) values <- numeric(6) for(i in 1:6){ values[i] <- dataf[samrow[i], samcol[i]] } However, I am not sure how to include the logical condition to only include postitive values Any help would be gratefully received. Jos ______________________________________________ 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.