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

[Prof Brian Ripley]

On Wed, 18 Jul 2007, Bill Dunlap wrote:

> On Wed, 18 Jul 2007 ripley at stats.ox.ac.uk wrote:
>
>> 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.
>
> write.dcf() is also used by print.packageDesription() so
> this change affects how missing fields are printed there.
> In 2.5 we got
>   > packageDescription("base", fields=c("Version","NoSuchField"))
>   Version: 2.5.0
>   NoSuchField: NA
>
>   -- File: /dept/devel/sw/R/R.linux.2.5.0/lib/R/library/base/DESCRIPTION
>   -- Fields read: Version, NoSuchField
> and now it doesn't print anything about the non-existant field
>   > packageDescription("base", fields=c("Version","NoSuchField"))
>   Version: 2.6.0
>   -- File: /homes/bill/R-svn/r-devel/R/library/base/DESCRIPTION
>   -- Fields read: Version, NoSuchField
> If this isn't acceptable then write.dcf will need a new argument
> to control the printing of missing lines.
>
> The missing trailing blank line is an inadvertant change (although
> it makes appending fields to a single record dcf file possible).

I've put in patches to address both of those issues.

Brian

>>> 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.
>>> ...
>>> 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,
>
>   [ The ==1 should be >=1 ]
>
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>

-- 
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