[R] RODBC package -- sqlQuery(channel,.....,nullstring=0) stillgives NA's

[Luis Rideau Cruz]

There is something strange in R behaviour (perhaps).

I have run the same select in Oracle SQL*Plus (version 10.1.0.2.0) and
the output comes out with NULLs  (which is what it ougth to be).

But in R I still get the same result with NAs (no matter I use
na.strings or nullstring arguments)
An output example follows below:

Using na.string="0"  and nullstring="0" (sorry by the indents):

   Length 2003 2002 2001 2000 1999 1998 1997 1996 1995
1      32   NA    1   NA   NA   NA   NA   NA    2   NA
2      34    3   NA   NA   NA   NA   NA   NA    6   NA
3      35   NA   NA   NA   NA    2   NA   NA   NA   NA
4      36   NA   12   NA   NA   10   NA   NA    1   NA
5      37    3    3   NA   NA    4   NA   NA   31   NA
6      38    2    4    1    1   12    6   NA   11   NA
7      39    4   13    5    5   34    8   NA   58   13

  Length 2003 2002 2001 2000 1999 1998 1997 1996 1995
       32                     1                                        
                        2
       34          3                                                   
                        6
       35                                                      2
       36                    12                               10       
                        1
       37          3          3                                4       
                       31
       38          2          4          1          1         12       
  6                    11
       39          4         13          5          5         34       
  8                    58         13


Best,
Luis


>>> Prof Brian Ripley <ripley at stats.ox.ac.uk> 12/01/2005 09:14:22 >>>
On Tue, 11 Jan 2005, Luis Rideau Cruz wrote:

> R-help,
>
> I'm using the RODBC package to retrieve data froma ODBC database
which
> contain NA's.
>
> By using the argument nullstring = "0"  in sqlQuery() I expect to
> coerce them to numeric but still get NA's in my select.

You need to read the help page (as the posting guide asks): it says

na.strings: character string(s) to be mapped to 'NA' when reading
           character data.

which is the opposite of what you are saying you want to do.

An ODBC database cannot contain NA's.  It may contain NULLs, and it may

contain "NA", so we have no idea what you mean.

-- 
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