[Rd] (PR#9796) write.dcf/read.dcf cycle converts missing entry

[ripley at stats.ox.ac.uk]

BIll,

Thanks.

I am seeing some problems here, for example when all the fields are 
missing, or all the fields in a row are missing.  I've fixes for those, 
and will commit to R-devel shortly.

On Tue, 17 Jul 2007, bill at insightful.com wrote:

> Full_Name: Bill Dunlap
> Version: 2.5.0
> OS: Red Hat Enterprise Linux WS release 3 (Taroon Update 6)
> Submission from: (NULL) (24.17.60.30)
>
>
> If you read a dcf file with read.dcf(file,fields=c("Field",...))
> and the file does not contain the desired field "Field",
> read.dcf puts a character NA for that entry in its output
> matrix.  If you then call write.dcf, passing it the output
> of read.dcf(), it will write the entry "Field: NA".  A subsequent
> read.dcf() on write.dcf's output file will then have a "NA",
> not a character NA, in the entry for "Field".  I think that
> write.dcf() should not write lines in the output file where
> the input matrix contains a character NA.
>
> Here is a test function to demonstrate the problem.  It returns
> TRUE when a write.dcf/read.dcf cycle does not change the data.
>
>  test.write.dcf <- function () {
>     origFile <- tempfile()
>     copyFile <- tempfile()
>     on.exit(unlink(c(origFile, copyFile)))
>     writeLines(c("Package: testA", "Version: 0.1-1", "Depends:", "",
>                  "Package: testB", "Version: 2.1"  , "Suggests: testA", "",
>                  "Package: testC", "Version: 1.3.1", ""),
>                origFile)
>     orig <- read.dcf(origFile,
>                      fields=c("Package","Version","Depends","Suggests"))
>     write.dcf(orig, copyFile, width = 72)
>     copy <- read.dcf(copyFile,
>                      fields=c("Package","Version","Depends","Suggests"))
>     value <- all.equal(orig, copy)
>     if (!identical(value, TRUE)) {
>        attr(value, "orig") <- orig
>        attr(value, "copy") <- copy
>     }
>     value
>  }
> Currently we get
>  > test.write.dcf()
>  [1] "'is.NA' value mismatch: 0 in current 4 in target"
>  attr(,"orig")
>       Package Version Depends Suggests
>  [1,] "testA" "0.1-1" ""      NA
>  [2,] "testB" "2.1"   NA      "testA"
>  [3,] "testC" "1.3.1" NA      NA
>  attr(,"copy")
>       Package Version Depends Suggests
>  [1,] "testA" "0.1-1" ""      "NA"
>  [2,] "testB" "2.1"   "NA"    "testA"
>  [3,] "testC" "1.3.1" "NA"    "NA"
> With the attached write.dcf() it returns TRUE.
>
> The diff would be
> 19,22c19,24
> <     eor <- character(nr * nc)
> <     eor[seq.int(1, nr - 1) * nc] <- "\n"
> <     writeLines(paste(formatDL(rep.int(colnames(x), nr), c(t(x)),
> <         style = "list", width = width, indent = indent), eor,
> ---
>>     tx <- t(x)
>>     not.na <- c(!is.na(tx))
>>     eor <- character(sum(not.na))
>>     eor[ c(diff(c(col(tx))[not.na]),0)==1 ] <- "\n"
>>     writeLines(paste(formatDL(rep.int(colnames(x), nr), c(tx),
>>         style = "list", width = width, indent = indent)[not.na], eor,
>
> and the entire function would be
>
> `write.dcf` <-
> function (x, file = "", append = FALSE, indent = 0.1 * getOption("width"),
>    width = 0.9 * getOption("width"))
> {
>    if (!is.data.frame(x))
>        x <- data.frame(x)
>    x <- as.matrix(x)
>    mode(x) <- "character"
>    if (file == "")
>        file <- stdout()
>    else if (is.character(file)) {
>        file <- file(file, ifelse(append, "a", "w"))
>        on.exit(close(file))
>    }
>    if (!inherits(file, "connection"))
>        stop("'file' must be a character string or connection")
>    nr <- nrow(x)
>    nc <- ncol(x)
>    tx <- t(x)
>    not.na <- c(!is.na(tx))
>    eor <- character(sum(not.na))
>    eor[ c(diff(c(col(tx))[not.na]),0)==1 ] <- "\n"
>    writeLines(paste(formatDL(rep.int(colnames(x), nr), c(tx),
>        style = "list", width = width, indent = indent)[not.na], eor,
>        sep = ""), file)
> }
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595