I am looking to erase an area in one shapefile by the area of another shapefile. After looking for as many resources as I can on this, I cannot get things to work.

def erase_shapes(self, to_erase, eraser, out_file):
    driver = ogr.GetDriverByName('ESRI Shapefile')
    feat1 = driver.Open(to_erase, 0)
    feat2 = driver.Open(eraser, 1)
    feat1Layer = feat1.GetLayer()
    feat2Layer = feat2.GetLayer()
    outDataSource = driver.CreateDataSource(out_file)

    out_ds = feat1Layer.Erase(feat1Layer, feat2Layer, outDataSource )
    out_ds = None

I am getting the following error:

ERROR 6: Only one feature iterator can be active at a time


numberVar = feat1Layer.GetFeatureCount()
numberVar = feat2Layer.GetFeatureCount()

it is confirmed that there is only 1 feature in each dataset.

When I try to add an iterator:

for feat in feat2Layer:
    out_ds = feat1Layer.Erase(feat1Layer, feat, outDataSource)
    out_ds = None

I get:

TypeError: in method 'Layer_Erase', argument 3 of type 'OGRLayerShadow *'

There is a lot of confusing information out there on how to get this to work. Any suggestions?

  • 1
    When posting code, don't just cut a method out of a class. Make it a complete and as runnable (as possible) example, including module imports and opening/setting of input data/variables etc.
    – user2856
    Jan 6, 2021 at 21:30

1 Answer 1


The Erase method signature is Erase(Layer self, Layer method_layer, Layer result_layer, optional args...)

You're doing two things incorrectly:

  1. Passing the input layer in twice, first implicitly (basic python, self is always passed to object methods, you don't explicitly pass it), then explicitly as the 1st argument;

  2. Passing a Dataset not a Layer as the result_layer argument.

Working example:

from osgeo import ogr

def erase_shapes(to_erase, eraser, out_file):
    feat1 = ogr.Open(to_erase)
    feat2 = ogr.Open(eraser)
    feat1Layer = feat1.GetLayer()
    feat2Layer = feat2.GetLayer()

    driver = ogr.GetDriverByName('ESRI Shapefile')
    outDataSource = driver.CreateDataSource(out_file)
    srs = feat1Layer.GetSpatialRef()
    outLayer = outDataSource.CreateLayer('', srs, ogr.wkbPolygon)

    out_ds = feat1Layer.Erase(feat2Layer, outLayer)
    out_ds = None

to_erase = "test1.shp"
eraser = "test2.shp"
out_file = "test3.shp"

erase_shapes(to_erase, eraser, out_file)

enter image description here

enter image description here

  • beauty. Thank you very much. If my eraser has multiple features, will I have to do a for loop?
    – D_C
    Jan 6, 2021 at 22:04
  • 1
    Yes the method_layer argument is a layer, not a feature so will use all features
    – user2856
    Jan 6, 2021 at 22:48

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