It turns out the code for loading covtype data seems take about
6 minutes on 1.2G AMD CPU XD , while a perl program takes only
about 2 minutes.
※ 引述《LCL2 (新年快热~)》之铭言：
: I did some modify to the above code for index support. It takes
: 3x sec on 1.2G AMD CPU for usps loading. But I don't think it's fast
: enough for hw3 still XD. Is there any other way? (any code problem please
: tell me, thanks)
: readData <- function (filename, ncolumn){
: lines <- readLines(filename)
: linenum <- length(lines)
: valueIndex <- 2*(1:ncolumn)-1
: indexIndex <- 2*(1:ncolumn-1)
: dataMatrix <- matrix(0,linenum, ncolumn)
: for(i in 1:linenum){
: tmp <- as.numeric(matrix(strsplit(lines[i], " +|:", perl=TRUE)[[1]]))
: dataTmp <- tmp[valueIndex]
: indexTmp <- tmp[indexIndex]
: iUsedIndex <- !is.na(indexTmp)
: dUsedIndex <- !is.na(dataTmp)
: dataMatrix[i, c(1, 1+indexTmp[iUsedIndex])] <- dataTmp[dUsedIndex]
: }
: return(dataMatrix)
: }
: tmp <- readData("usps", 257)