Python Nested select by attribute and location slow

ClaireElliott

Hello, I'm trying to make a simple script to loop through a list of properties (~700), selecting one at a time, and then select the intersecting features (there's 21 feature classes) and print them to screen. When i execute this script, it starts slowing down each time it goes to a new property. By property 15/700, it's already taking a few seconds for the "HAVE_THEIR_CENTRE_IN" select by location method. I feel there's something obvious I'm missing, or not resetting/cleaning up between each iteration in my loop.

 

Thank you for any help/advice.

 

import arcpy
import os

Property = r'C:\Boundaries.gdb\Property'
FeatureClasses = r'C:\FieldData.gdb'

properties = [row[0] for row in arcpy.da.SearchCursor(Property, 'NAME')]

arcpy.env.workspace = FeatureClasses

fcList = arcpy.ListFeatureClasses()

for prop in properties:
    whereClause = "NAME = '"+prop+"'"
    selectedProp = arcpy.management.SelectLayerByAttribute(Property, "NEW_SELECTION", whereClause)
    print('property: '+prop)
    for fc in fcList:
        selectedFeatures = arcpy.management.SelectLayerByLocation(os.path.join(FeatureClasses, fc), "HAVE_THEIR_CENTER_IN", selectedProp)
        print('fc: ' + str(fc) + ' and found "' + str(len(selectedFeatures)) + '"')

 

Anonymous User

For giggles, you can also break this up into multiprocessing. You'll have to modify the sql query/ fc stuff for it to work with your structure but its about the same process.

This file is name IntersectWorker:

# Import modules
import os.path
from arcpy import management

# -------------------------------------------------------------------------------
def get_intersect_count(feature, selFc, testFc):
    """
    Function to return intersecting features
    """
    try:
        whereClause = f"OBJECTID = {feature}"
        selectedProp = management.SelectLayerByAttribute(selFc, "NEW_SELECTION", whereClause)

        selectedFeatures = management.SelectLayerByLocation(testFc, "INTERSECT", selectedProp)

        return {'feature': feature, 'testFc': os.path.basename(testFc), 'count': selectedFeatures[2], 'msg': 'success'}

    except Exception as ex:
        return {'feature': feature, 'testFc': os.path.basename(testFc), 'count': 0, 'msg': ex}

 

This is the main file named IntersectMain:

# Import modules
import os
from arcpy import da
from arcpy import env
from arcpy import ListFeatureClasses
from multiprocessing import Pool
import multiprocessing as mp
from IntersectWorker import get_intersect_count

if __name__ == "__main__":

    selFc = r'path to the selecting fc'

    basePath = r'path to the .gdb'

    env.workspace = basePath
    fcList = ListFeatureClasses(feature_type='Polygon')

    argsList = []

    for prop in [row[0] for row in da.SearchCursor(selFc, ['OBJECTID'])]:
        for fc in fcList:
            args = (prop, selFc, os.path.join(basePath, fc))
            argsList.append(args)

    with Pool(mp.cpu_count() - 1) as pool:
        result = pool.starmap(get_intersect_count, argsList)

    for res in result:
        if res['msg'] == 'success':
            print(f'feature: {res["feature"]} found: {res["count"]}  features in {res["testFc"]}')
        else:
            print(f'intersecting features in {res["testFc"]} failed with {res["msg"]}')