[R] spare matrix replacing values efficiently

I am working with a large sparse matrix trying replace all 1 values with 0. The normal method doesn't work. Here is a small example: > x <- Matrix(0,nrow=10,ncol=10,sparse=TRUE) > x[,1] <- 1:2 > x 10 x 10 sparse Matrix of class "dgCMatrix" [1,] 1 . . . . . . . . . [2,] 2 . . . . . . . . . [3,]

[R] incrementing matrix elements more efficiently

I need to increment cells of a matrix (collusionM). The indexes to increment are in an index (matchIndex). This is sample code library(seqinr) library(Matrix) x <- "abcabcabc" mx <- s2c(x) collisionM <- Matrix(0,nrow=10, ncol=10, sparse=TRUE) matchIndex <- list() rows <-

[R] incrementing matrix elements more efficiently

I need to increment cells of a matrix (collusionM). The indexes to increment are in an index (matchIndex). This is some of the code for (j in 1:(rows-1)) matchIndex[[j]] <- which(mx[j]==mx) for (j in 1:(rows-1)) collisionM[j,matchIndex[[j]]] <- collisionM[j,matchIndex[[j]]] + 1

[R] efficient matrix element comparison

It is a simple problem in that I simply want to convert the For loop to a more efficient method. It simply loops through a large vector checking if the numeric element is not equal to the index of that element. The following example demonstrates a simplified example: > rows <- 10 > collusionM

[R] subset of string by index

How can I get a substring based on the index into the string? strM <- c("abcde", "cdefg") ind <- c(1,3,5) I want to use ind to index into the strings so the result is: strMind <- c("ace", "ceg") __ R-help@r-project.org mailing list https://stat.ethz.c

[R] subset of string by index

How can I get a substring based on the index into the string? strM <- c("abcde", "cdefg") ind <- c(1,3,5) I want to use ind to index into the strings so the result is: strMind <- c("ace", "ceg") __ R-help@r-project.org mailing list https://stat.ethz.c