read.table, read.fwf, and na.strings (PR#7075)

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Is this intended behavior for the read.fwf(na.strings="-999")?
I anticipated that the na.strings would be padded with blanks.
Therefore I anticipated getting the result tmp2 from the simpler
na.strings in the tmp1 assignment?  My anticipation is based on the
documentation that says
"Blank fields are also considered to be missing values."

na.strings: a vector of strings which are to be interpreted as 'NA'
         values.  Blank fields are also considered to be missing
         values.

temp.dat
A blank field in the first column of the first row is:

   3456-999 01234
56-9990123412345

The field "-999 " cannot assumed to be blank in any sence from my point
of view.

Anyway, improving NA handling in read.fwf() is certainly something for
the wishlist (particularly padding blanks for na.string(s)). Is anybody
out there going to contribute (given anybody else thinks it is useful)?

Uwe Ligges
----------------
123456-999 01234
56-9990123412345
----------------

read.fwf.test.r
------------------------------------------------
tmp1 <- read.fwf("temp.dat",
                 na.strings="-999",
                 col.names=LETTERS[1:4],
                 widths=c(2,4,5,5))
tmp1
tmp2 <- read.fwf("temp.dat",
                 na.strings=c("-999","-999 "),
                 col.names=LETTERS[1:4],
                 widths=c(2,4,5,5))
tmp2
------------------------------------------------

tmp1
   A    B    C     D
1 12 3456 -999  1234
2 56   NA 1234 12345

tmp2
   A    B    C     D
1 12 3456   NA  1234
2 56   NA 1234 12345

--please do not edit the information below--

Version:
 platform = i386-pc-mingw32
 arch = i386
 os = mingw32
 system = i386, mingw32
 status = 
 major = 1
 minor = 9.1
 year = 2004
 month = 06
 day = 21
 language = R

Windows XP Home Edition (build 2600) Service Pack 1.0

Search Path:
 .GlobalEnv, file:c:/HOME/rmh/hh/splus.library/HH/.RData, package:methods, package:stats, 
package:utils, package:multcomp, package:mvtnorm, package:abind, package:graphics, 
package:lattice, package:grid, Autoloads, package:base

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