[R] Accelerating binRead

[Bob Rudis]

You should probably pick a forum — here or SO :
http://stackoverflow.com/questions/39547398/faster-reading-of-binary-files-in-r
: - vs cross-post to all of them.

On Sat, Sep 17, 2016 at 11:04 AM, Ismail SEZEN <sezenismail at gmail.com>
wrote:

> I noticed same issue but didnt care much :)
>
> On Sat, Sep 17, 2016, 18:01 jim holtman <jholtman at gmail.com> wrote:
>
> > 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]]
> >
> > ______________________________________________
> > 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]]
>
> ______________________________________________
> 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.
>

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