[R] RODBC package -- sqlQuery(channel,.....,nullstring=0) stillgives NA's
Prof Brian Ripley
ripley at stats.ox.ac.uk
Wed Jan 12 12:21:33 CET 2005
PLEASE do read the help page, which says
nullstring: character string to be used when reading 'SQL_NULL_DATA'
character items from the database.
^^^^^^^^^^^^^^^
so this does not apply to numeric items.
You can of course easily change numeric NAs to 0s, if you want to.
On Wed, 12 Jan 2005, Luis Rideau Cruz wrote:
> There is something strange in R behaviour (perhaps).
Your negative remarks are not appreciated.
> 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
>
>
--
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
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