test_qgsvectordataprovider.py

Daniel Vaz, 2013-07-07 08:11 AM

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from qgis.core import *
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QgsApplication.setPrefixPath('/usr/local', True)


    		
  

  

    
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QgsApplication.initQgis()


    		
  

  

    
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# load a layer


    		
  

  

    
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vlayer = QgsVectorLayer('polygons.shp', 'layer_name', 'ogr')


    		
  

  

    
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if vlayer.isValid():


    		
  

  

    
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  print 'layer is valid'


    		
  

  

    
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  # get the data provider


    		
  

  

    
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  vprovider = vlayer.dataProvider()


    		
  

  

    
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  # get index of field 'name' 


    		
  

  

    
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  name_index = vprovider.fieldNameIndex('name')


    		
  

  

    
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  # there are NULL values in the field 'name' on sample dataset


    		
  

  

    
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  unique = vprovider.uniqueValues(name_index)


    		
  

  

    
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  print unique