Hello, the following function, which stores numeric values extracted from a binary file, into an R matrix, is very slow, especially when the said file is several MB in size. Should I rewrite the function in inline C or in C/C++ using Rcpp? If the latter case is true, how do you « readBin » in Rcpp (I’m a total Rcpp newbie)? Many thanks. Best regards, phiroc
------------- # inputPath is something like http://myintranet/getData?pathToFile=/usr/lib/xxx/yyy/data.bin <http://myintranet/getData?pathToFile=/usr/lib/xxx/yyy/data.bin> PLTreader <- function(inputPath){ URL <- file(inputPath, "rb") PLT <- matrix(nrow=0, ncol=6) compteurDePrints = 0 compteurDeLignes <- 0 maxiPrints = 5 displayData <- FALSE while (TRUE) { periodIndex <- readBin(URL, integer(), size=4, n=1, endian="little") # int (4 bytes) eventId <- readBin(URL, integer(), size=4, n=1, endian="little") # int (4 bytes) dword1 <- readBin(URL, integer(), size=4, signed=FALSE, n=1, endian="little") # int dword2 <- readBin(URL, integer(), size=4, signed=FALSE, n=1, endian="little") # int if (dword1 < 0) { dword1 = dword1 + 2^32-1; } eventDate = (dword2*2^32 + dword1)/1000 repNum <- readBin(URL, integer(), size=2, n=1, endian="little") # short (2 bytes) exp <- readBin(URL, numeric(), size=4, n=1, endian="little") # float (4 bytes, strangely enough, would expect 8) loss <- readBin(URL, numeric(), size=4, n=1, endian="little") # float (4 bytes) PLT <- rbind(PLT, c(periodIndex, eventId, eventDate, repNum, exp, loss)) } # end while return(PLT) close(URL) } ---------------- [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
