[Gdal-dev] easy ogr question...

[Dan Putler]

Hi Will,

I add new fields to shapefiles all the time. Although, I do it using  
R, which (through Frank's shapelib) handles DBFs beautifully. I can  
provide details, but since this is now off list, I can provide  
details privately. The main thing is that you only need to muck with  
the *.dbf file, not the *.shp file itself.

Dan

On 19-Sep-06, at 9:33 AM, Will Cadell wrote:

> Thanks Frank,
>
> No message I'm afraid but there are features, and I was wondering how
> ogr would handle and 'empty' column. I assumed it would add nulls, but
> hey ho seems like I'll have to make a new shapefile, copy the layer
> definition then add the field then copy all the features to a new
> shapefile... Does seem a bit cumbersome though... is there a better  
> way
> people can think of?
>
> will
>
> Frank Warmerdam wrote:
>> Will Cadell wrote:
>>> hi guys... am i just stupid or is there another way to add a  
>>> field to a
>>> shapefile other than:
>>>        ds = ogr.open("c:\shapefile.shp", True)
>>>        new_field = ogr.FieldDefn()
>>>     new_field.SetName(new_field_name)
>>>     new_field.SetType(new_field_type)
>>>     new_field.SetWidth(new_field_width)
>>>        layer = ds.GetLayer(0)
>>>     layer.CreateField(new_field)
>>>        ds.destroy
>>>
>>> because this doesn't work for me...
>>
>> Will,
>>
>> This does seem like the correct approach.  Are there any features  
>> in the
>> shapefile already?  I'm pretty sure that adding a field only works  
>> when
>> there are no features yet.  If you aren't getting an error message  
>> then
>> there is a clear bug here, and a bug report in bugzilla would be
>> appreciated.
>>
>> Best regards,
>
> -- 
> Will Cadell
> Remote Sensing and GIS Analyst
>
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