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I'm fairly new to using PyQgis, so sorry if this question is basic. I'm working with two vector layers:

(layer 1) A series of polygons, each with an ID field specifying what geographic district the polygon is in

(layer 2) A series of points, also with the same ID field as above

I am trying to determine what points from layer 2 lie within a polygon with a matching ID field from layer 1.

As a start, I decided I would loop over all of the polygons in layer 1, and for each polygon, loop over all of the points in layer 2 to see if the ID fields of each polygon/point matched. The ID field in layer 1 is attribute number 10. The corresponding ID field in layer 2 is attribute number 1. My problem is that, in the following code, only the first feature in layer 1 gets looped over. So, while there are about 200 or so polygons in layer 1, each with a unique ID, the code only loops over a single ID corresponding to a single polygon.

Here's what I have:

layer1 = QgsVectorLayer('shapefile1_location', "polygon_layer")
if not layer1:
  print "Layer 1 failed to load!"

layer2 = QgsVectorLayer('shapefile2_location', "points_layer")
if not layer2:
  print "Layer 2 failed to load!"


layer1 = iface.addVectorLayer('shapefile1_location', "polygon_layer", "ogr")
layer2 = iface.addVectorLayer('shapefile2_location', "points_layer", "ogr")


iter1 = layer1.getFeatures()
iter2 = layer2.getFeatures()
for polygon in iter1:
    for point in iter2:
        if polygon[10]==point[1]:
            print polygon[10], "Success!"
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  • Detlev is right. Also, to test if the point lies within the polygon you could do it like this: polygon.geometry().contains(point.geometry()). Commented Oct 26, 2015 at 12:15

1 Answer 1

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QgsVectorLayer.getFeatures() is an iterator that yields the next value each time it is called. Therefore you must call it repeatedly to iterate through all possible values.

Change your code as following:

for polygon in layer1.getFeatures():
    for point in layer2.getFeatures():
        if polygon[10]==point[1]:
            print polygon[10], "Success!"

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