You could randomly assign 1 to a single column in each row and then use binomial draws on the remaining 0's:
> set.seed(42) > dimMat <- matrix(0, 1000, 4) > dimMat[cbind(1:1000, sample.int(4, 1000, replace=TRUE))] <- 1 > dimMat[dimMat<1] <- sample(0:1, 3000, replace=TRUE, prob=c(.6, .4)) > table(rowSums(dimMat)) 1 2 3 4 217 402 310 71 > colSums(dimMat) [1] 551 586 533 565 > sum(dimMat) [1] 2235 ------------------------------------- David L Carlson Department of Anthropology Texas A&M University College Station, TX 77840-4352 -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of Doran, Harold Sent: Wednesday, April 9, 2014 3:56 PM To: r-help@r-project.org Subject: [R] Generate Binary Matrix I am trying to generate a binary matrix where every row in the matrix is guaranteed to have at least one 1. Ideally, I would like most rowSums to be equal to 2 or 3 with some 1s and some 4s. But, rowSums cannot be equal to 0. I can tinker with the vector of probability weights, but in doing so (in the way I am doing it) this causes for more rowSums to be equal to 4 than I ideally would like, but this never helps to guarantee a rowSum will not be equal to 0. I could post-hoc tinker with any rows that are all 0, but seems like that may be just inefficient. Below is sample code, any ideas on how to best tackle this? Harold dimMat <- matrix(0, 1000, 4) for(i in 1:1000){ dimMat[i, ] <- sample(c(0,1), 4, replace = TRUE, prob = c(.3, .7)) } table(rowSums(dimMat)) [[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. ______________________________________________ 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.
