Hi Ken, If your lists are not too large something such as this can work:
> matrixFromList <- function(listX) t(sapply(listX, function(x, n) c(x, rep(NA, > n))[1:n], n = max(sapply(listX, length)))) > matrixFromList(list(c(3,2,3),c(6,5))) [,1] [,2] [,3] [1,] 3 2 3 [2,] 6 5 NA > A <- list(c(3,2,3), c(1,2,3,4), c(5,6)) > matrixFromList(A) [,1] [,2] [,3] [,4] [1,] 3 2 3 NA [2,] 1 2 3 4 [3,] 5 6 NA NA > class(matrixFromList(A)) [1] "matrix" Best Steven McKinney Statistician Molecular Oncology and Breast Cancer Program British Columbia Cancer Research Centre email: smckinney +at+ bccrc +dot+ ca tel: 604-675-8000 x7561 BCCRC Molecular Oncology 675 West 10th Ave, Floor 4 Vancouver B.C. V5Z 1L3 Canada -----Original Message----- From: r-help-boun...@r-project.org on behalf of Lo, Ken Sent: Wed 1/14/2009 1:50 PM To: r-help@r-project.org Subject: [R] coercing a list into matrix Dear list, I have a list of number sequences. Each number sequence has different numbers of elements. Is there a quick way (other than to iterate through the entire list) way to coerce list to matrix with NAs filling in the short sequences? An example of what I mean is this: A <- list(c(3,2,3),c(6,5)) I'd like to get A so that it is 3 2 3 6 5 NA Best, Ken ______________________________________________ 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.