I have two layers with 20+ polygon features, layer1 and layer 2. I would like to extract attributes from all of the features in layer 2 that are within 1km of layer 1, for each feature in layer 1. I am doing this by iterating through the features in layer 1, and buffering each feature by 1km. Within this loop, I am iterating through the features in layer 2, and checking whether these features intersect with the 1km buffer:

for lyr in QgsMapLayerRegistry.instance().mapLayers().values():
    if lyr.name() == "@@@@@":
        layer 1 = lyr

for lyr2 in QgsMapLayerRegistry.instance().mapLayers().values():
    if lyr2.name() == "@@@@2":
        targetlayer = lyr2

siteboundaryshapes = siteboundary.getFeatures()
targetlayershapes = targetlayer.getFeatures()

for count,i in enumerate(siteboundaryshapes):
    siteboundarygeom = i.geometry()
    siteboundarybuffer = siteboundarygeom.buffer(1000,25)
    siteboundaryatt = i.attributes()
    print (siteboundaryatt[1])

    for j in targetlayershapes:
        targetlayergeom = j.geometry()
        targetlayeratt = j.attributes()

    if targetlayergeom.intersects(siteboundarybuffer):
        print (targetlayeratt[1])

I am trying to return the attributes of the features in layer 2 that intersect with the buffer on layer 1 in the following format:

layer 1 feature 1 attribute

layer 1 feature 2 attribute
layer 2 feature 1 attrbute
layer 2 feature 2 attribute

layer 1 feature 3 attribute
layer 2 feature 1 attribute

layer 1 feature 4 attribute
layer 2 feature 1 attribute

etc etc

layer 1 feature 20 attribute

The above currently does not work; it loops through all of the features in layer 1, but only returns attributes for layer 2 in the first instance that layer 2 intersects with the buffer in layer 1. I have tried moving the indent of the if statement, but this just loops through the features in layer 2 for the first feature in layer 1 and then stops looping through layer 2 thereafter.


I would make sure you were using an index to cut down on needing to go through the whole 2nd layer each time.

Something like this should do it:

from qgis.core import *
import processing

layer1 = processing.getObject('ne_10m_populated_places')
layer2 = processing.getObject('ne_10m_admin_0_countries')

all_features = {}
index = QgsSpatialIndex() # Spatial index
for ft in layer1.getFeatures():
    all_features[ft.id()] = ft

selection = [] # This list stores the features which contains at least one point
features = layer2.getFeatures()
for feat in features:
    inGeom = feat.geometry().buffer(1000,25)
    idsList = index.intersects(inGeom.boundingBox())
    #print "found %d points"%len(idsList)
    for id in idsList:
        testGeom = all_features[id].geometry()
        testGeomP = testGeom.asPoint()
        #print testGeomP.x(),testGeomP.y()
        if inGeom.intersects(testGeomP):
            if feat not in selection:
                selection.append( all_features[id])

# Select all the polygon features which contains at least one point
layer1.setSelectedFeatures([k.id() for k in selection])

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