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I am new to Python programming.

How do I check the intersection of two shapefiles using ArcPy?

If the shapefiles intersect, it should return True else False.

Below is the code that I have written :

import arcpy

arcpy.env.workspace = "D:/Qasim/mn_corcoran"

arcpy.Intersect_analysis(r'D:/Qasim/mn_hopkins/abc.shp #;D:/Qasim/mn_corcoran/xyz.shp #', r'D:/Qasim/mn_hopkins/asd.shp', 'ALL', '#', 'INPUT')

if arcpy.Intersect_analysis == True:
  
 print("True")

else: arcpy.Intersect_analysis == False

print("False")
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1
  • ArcGIS is geared toward comparing features not feature classes. You should review documentation associated with the spatial selection tools, and selection set management.
    – Vince
    Aug 31, 2020 at 12:08

2 Answers 2

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1

You can "catch" the result object returned by Intersect.

For example:

import arcpy
arcpy.env.workspace = r'C:\shapefile_folder'
result = arcpy.Intersect_analysis(["ak_riks.shp","ak_riks_Dissolve.shp"],r'in_memory\intersection')

And then use getMessages():

result.getMessages()
u'Executing: Intersect "ak_riks #;ak_riks_Dissolve #" in_memory\\intersection ALL # INPUT\nStart Time: Mon Aug 31 12:32:47 2020\nReading Features...\nCracking Features...\nAssembling Features...\nWARNING 000117: Warning empty output generated.\nSucceeded at Mon Aug 31 12:32:47 2020 (Elapsed Time: 0,14 seconds)'

'empty output' not in result.getMessages()
False

enter image description here

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2
  • 1
    Using Intersect_analysis to test for dataset overlap is like crashing your car into a shopping mall to see if the Pier 1 Imports is still open. Instead of creating a new dataset to be discarded, the OP's stated goal could be achieved with an envelope test.
    – Vince
    Aug 31, 2020 at 12:28
  • 1
    I know. It does not matter if the analysis take 2 min or 30 s unless you have to do the comparison often
    – BERA
    Aug 31, 2020 at 12:29
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You can do it by counting intersect features. If intersect returns some features, then result is True, else False. The code can be:

import arcpy

arcpy.env.workspace = "D:/Qasim/mn_corcoran"

intersect_layer = arcpy.Intersect_analysis(r'D:/Qasim/mn_hopkins/abc.shp #;D:/Qasim/mn_corcoran/xyz.shp #',
                         r'D:/Qasim/mn_hopkins/asd.shp', 'ALL', '#', 'INPUT')

if int(arcpy.GetCount_management(intersect_layer)[0]) > 0:
    print("True")
else:
    print("False")
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7
  • This could be a heinously expensive way to know that a contour feature class overlays with a soils feature class. I know the OP used the Intersect_analysis tool, but it's the wrong tool for the task, so answers should address the root problem, which could be as simple as testing envelopes before attempting a spatial selection.
    – Vince
    Aug 31, 2020 at 12:16
  • @Vince Then please elaborate , what should be done in order to check intersection of two shapefiles using ArcPy? if you have a sample code discussing this type of problem , share it here then.
    – Muhammad Qasim
    Aug 31, 2020 at 12:27
  • @david_p It gives FALSE in return in every condition even if there are intersected features. It should give TRUE also when there are intersected features between two shapefiles.
    – Muhammad Qasim
    Aug 31, 2020 at 12:38
  • 1
    @muhammad It depends on "intersect_layer". If its empty, it should return False. If it contains some features (even only one), it should return True. Try to inspect this layer if it is empty or not.
    – david_p
    Aug 31, 2020 at 13:17
  • @david_p The layer has some features , still FALSE is returning everytime. Have you tried this method with any shapefiles???
    – Muhammad Qasim
    Sep 1, 2020 at 4:08

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