Hello everyone, I need to create and work with some big matrices that actually have somewhat over 2 million columns and 117 rows. To do some calculations on such big matrices R just needs too much memory for my PC (4GB installed). So I need a solution to work with large datasets. I'm trying to use the ff-package but I don't think I really understand the whole functionality of the package. Hopefully someone can help me either with the ff-package or a different solution.
I am saving some calculated matrices as ff-objects as follows: require(ff) nr <- 117; nc <- 50 dat <- sample(0:100, size=(nr*nc), replace=TRUE) a <- matrix(dat, nrow=nr) ncols <- (nc*(nc-1))/2 b <- ff(vmode="double", dim=c(nr, ncols)) namb <- vector(mode="character", length=ncols) x <- 1 for(i in 1:(nc-1)){ for(j in (i+1):nc){ b[,x] <- a[,i]+a[,j] namb[x] <- paste(i, "_", j, sep="") x <- x+1 } } dimnames(b)[[2]] <- namb After the above step I need to convert my ff_matrix to a data.frame to discretize the whole matrix and calculate the mutual information. The calculated result should be saved as an ffdf-object or something similar. require(infotheo) disc <- as.ffdf(discretize(as.data.frame(as.ffdf(cc)), disc="equalwidth", nbins=5)) This won't work. After this step it somehow loses the path to the working directory. As soon as I try to discretize the next data.frame I get the following message: Error in if (dfile == getOption("fftempdir")) finalizer <- "delete" else finalizer <- "close" : Argument has length 0 Error in setwd(cwd) : character as argument expected I would be really glad if anybody can help me understanding the functionality and show me how to convert between the different data types. Thanks in advance, Anne S. ______________________________________________ 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.