[R] exporting long character vectors to dbf

[Prof Brian Ripley]

On Wed, 24 May 2006, Mulholland, Tom wrote:

> I assume this is (or was) a specification issue. I think write.dbf uses 
> the shapefile library (C not R library) so it applies to the use of 
> shapefiles and just happens to have been included in the foreign package 
> because it has a generic usefullness. (Is that a word?)

Actually, the width of the dbf field comes from the lines in write.dbf:

         else if (is.character(x)) {
             mf <- max(nchar(x[!is.na(x)]))
             precision[i] <- min(max(nlen, mf), 254)
             scale[i] <- 0

so that's the limit (254, not 255).  This is stated as a limitation of the 
dbf format at 
http://www.clicketyclick.dk/databases/xbase/format/data_types.html
so I don't think you can do what you want with .dbf.

> Since I very rarely care about the elegance of my solutions, just that 
> they work, I would try saving the file in another format that you can 
> get open office to read and let it do the conversion rather than trying 
> to get R to do it. I'm sure OpenOffice can deal with straightforward 
> text files if that's a last resort.

Indeed.  Using an ODBC driver (and RODBC) to write to the database might 
be a good option.

>
> Tom
>
>> -----Original Message-----
>> From: r-help-bounces at stat.math.ethz.ch
>> [mailto:r-help-bounces at stat.math.ethz.ch]On Behalf Of Eduardo Leoni
>> Sent: Wednesday, 24 May 2006 7:13 AM
>> To: r-help at stat.math.ethz.ch
>> Subject: [R] exporting long character vectors to dbf
>>
>>
>> Hi -
>>
>> I need to export data to openoffice base, where one of the elements is
>> a long character vector (>255 characters.) write.dbf exports it as
>> varchar, truncating the data. Any idea how to do this?
>>
>> thanks,
>>
>> -eduardo
>>
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>
> ______________________________________________
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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