[R] Accelerating binRead

[jim holtman]

Your example was not reproducible.  Also how do you "break" out of the
"while" loop?


Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.

On Sat, Sep 17, 2016 at 8:05 AM, Philippe de Rochambeau <phiroc at free.fr>
wrote:

> 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 at 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.

	[[alternative HTML version deleted]]