Hi everyone, my apologies if I'm overlooking something obvious in the documentation. I'm relatively inexperienced with the (awesome) ff package.
My goal is to use the read.table.ffdf() function to call the read.fwf() function and pass through the colClasses and comment.char arguments. The code below shows exactly what doesn't work for me. If the colClasses and comment.char parameters cannot be passed to read.fwf() through read.table.ffdf(), I'd love to hear any ideas for a workaround? :) Passing the comment.char parameter isn't critical for what I'm doing, so long as read.table.ffdf() is in fact passing comment.char = '' through to read.fwf(), as stated in (5) of the Details section of the documentation<http://www.inside-r.org/packages/cran/ff/docs/read.table.ffdf>. I do not want comment.char = "#" -- the default for read.table(). I'm using R 2.15.1 x86_64-pc-mingw32/x64 (64-bit) on Windows 7. Thanks!! Anthony Damico Kaiser Family Foundation library(ff) # create a simple temporary file.. fwffile <- tempfile() # steal some example code from the documentation -- cat(file=fwffile, "123456", "987654", sep="\n") x <- read.fwf(fwffile, widths=c(1,2,3)) #> 1 23 456 \ 9 87 654 y <- read.table.ffdf(file=fwffile, FUN="read.fwf", widths=c(1,2,3)) stopifnot(identical(x, y[,])) # the above block of code obviously works # then if i want to add the colClasses parameter, # read.fwf() works on its own u <- read.fwf(fwffile, widths=c(1,2,3) , colClasses = 'factor' ) #> 1 23 456 \ 9 87 654\ # but read.table.ffdf() does not. v <- read.table.ffdf(file=fwffile, FUN="read.fwf", widths=c(1,2,3) , colClasses = 'factor' ) # i'm confused why the line above doesn't work, since read.csv.ffdf() has no problem passing colClasses through to read.csv.. # as seen in this example (a slightly modified version of the documentation) x <- data.frame(log=rep(c(FALSE, TRUE), length.out=26), int=1:26, dbl=1:26 + 0.1, fac=factor(letters), ord=ordered(LETTERS), dct=Sys.time()+1:26, dat=seq(as.Date("1910/1/1"), length.out=26, by=1)) x <- x[c(13:1, 13:1),] csvfile <- tempPathFile(path=getOption("fftempdir"), extension="csv") write.csv(x, file=csvfile, row.names=FALSE) y <- read.csv(file=csvfile, header=TRUE, colClasses=c(dct="POSIXct", dat="Date")) # "ordered" gives an error ffx <- read.csv.ffdf(file=csvfile, header=TRUE, colClasses=c(dct="POSIXct", dat="Date")) identical( y , ffx[ , ] ) [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list 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.
