[OSGeo-Discuss] methods for programatically adding fields to shapefiles

[Tim Sutton]

Hi

Are there any suggestions on how to do this from c++? Something we've
long wanted to add support for in QGIS.....

Frank Warmerdam was reticent about adding it to ogr since it would
have many crosscutting implications...

Regards

Tim

2008/10/31 Tyler Erickson <tyler.erickson at mtu.edu>:
>
> Thanks for all the suggestions.  Although it is still a work in progress,
> it's looking like the ogr library approach suggested by David will work out
> for me...
>
> - Tyler
>
>
> def create_formatted_shapefile_using_ogr(infile, outfile):
>
>    # setup a spatial reference
>    srs_out = osr.SpatialReference()
>    srs_out.SetFromUserInput('WGS84')
>
>    ogrdriver = ogr.GetDriverByName('ESRI Shapefile')
>
>    dsInput = ogrdriver.Open(infile)
>    mLayer = dsInput.GetLayer()
>    featureCount = mLayer.GetFeatureCount()
>
>    # create the output shapefile
>    if os.path.exists(outfile):
>        ogrdriver.DeleteDataSource(outfile)
>    dsOutput = ogrdriver.CreateDataSource(outfile)
>    outLayer = dsOutput.CreateLayer(dsOutput.GetName(), \
>                                geom_type = ogr.wkbPolygon, \
>                                srs = srs_out)
>    outLayer.CreateField(ogr.FieldDefn('start_date', ogr.OFTDate))
>    outLayer.CreateField(ogr.FieldDefn('fire_code', ogr.OFTString))
>    outLayer.CreateField(ogr.FieldDefn('fire_name', ogr.OFTString))
>    outLayer.CreateField(ogr.FieldDefn('source', ogr.OFTString))
>
>    print 'FeatureCount = ' + str(featureCount)
>
>    for iFeature in range(0,mLayer.GetFeatureCount()):
>        inFeature = mLayer.GetFeature(iFeature)
>
>        geom = inFeature.GetGeometryRef()
>        start_date = inFeature.GetFieldAsString('year') + "-" + \
>                    inFeature.GetFieldAsString('startmonth') + "-" + \
>                    inFeature.GetFieldAsString('startday')
>
>        # reproject to WGS84
>        geom.TransformTo(srs_out)
>
>        # write the attributes to the output file
>        outFeature = ogr.Feature(feature_def=outLayer.GetLayerDefn())
>        outFeature.SetGeometry(geom)
>        outFeature.SetFID(1)
>        outFeature.SetField('fire_code', inFeature.GetField('fire_id'))
>        outFeature.SetField('fire_name', inFeature.GetField('fire_name'))
>        outFeature.SetField('source', infile)
>        outLayer.CreateFeature(outFeature)
>
>        outFeature.Destroy()
>        inFeature.Destroy()
>
>    dsInput.Destroy()
>    dsOutput.Destroy()
>
>
> --
> View this message in context: http://n2.nabble.com/methods-for-programatically-adding-fields-to-shapefiles-tp1395535p1437802.html
> Sent from the OSGeo Discuss mailing list archive at Nabble.com.
>
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> Discuss mailing list
> Discuss at lists.osgeo.org
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>



-- 
Tim Sutton - QGIS Project Steering Committee Member (Release  Manager)
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