topic Re: Selecting points not within polygons in arcpy in Python Questions

Selecting points not within polygons in arcpy

blob — Fri, 28 Jun 2024 12:12:34 GMT

Dear community,

I am having problems selecting points from a layer which are not within another polygon layer. I have tried using arcpy.SelectLayerByLocation_management(point, 'WITHIN', poly, '', 'NEW_SELECTION', 'INVERT'), but it has not yielded the desired results.

To test this functionality, I have created the MWE below.

import arcpy def main(): arcpy.env.workspace = arcpy.env.scratchGDB arcpy.env.overwriteOutput = True poly = 'test.gdb/test_poly' point = 'test.gdb/test_point' arcpy.SelectLayerByLocation_management(point, 'WITHIN', poly, '', 'NEW_SELECTION', 'INVERT') point_select = 'point_select' arcpy.CopyFeatures_management(point, point_select) arcpy.SelectLayerByAttribute_management(point, selection_type='CLEAR_SELECTION') if __name__ == "__main__": main()

For which I also have created a new database with a point (5 features) and polygon (1 features) layer:

I have also created a new tool to test this with, for which I am getting the output (with some small print statements added):

Which suggests that no selection is being done. Using the Select By Location tool within ArcGIS Pro (the same equivalent?) the selection works:

Things I have tried:

Substituting the operation ('INTERSECT', 'COMPLETELY_WITHIN')
Clearing the cache (Project > Options > Application > Display > Local Cache > Clear Cache Now)
Restarting ArcGIS / reloading tool
Clearing / not clearing the selection after copying features
Using layers in scratch.gdb / actual database
Setting the method arguments using their names (in_layer=..., overlap_type=..., etc.)
Switching 'INVERT' / 'NOT_INVERT' but none of them affect the results, i.e. no selection

Am I misunderstanding how this method works, or is there some other explanation for the selection not working?

Re: Selecting points not within polygons in arcpy

RichardHowe — Fri, 28 Jun 2024 12:25:46 GMT

You are running your python on feature class inputs, not feature layers (which is what you're running the tool in Pro on). A feature layer is a temporary construct within a Pro session which gives you a view, symbology etc of your feature class.

Use the Make Feature Layer tool first in your script, then use the two layers you create as your inputs for the select by location and I suspect you will have more success.

Or (as I can see you've attached it to a toolbox) make the inputs for the tool "feature layers" allowing you to drag and drop from your table of contents

Re: Selecting points not within polygons in arcpy

AlfredBaldenweck — Fri, 28 Jun 2024 12:55:49 GMT

That's a good point. I'd also try assigning the selection to a variable to pass into copy(). See Lines 11 and 14.

import arcpy def main(): arcpy.env.workspace = arcpy.env.scratchGDB arcpy.env.overwriteOutput = True poly = 'test.gdb/test_poly' point = 'test.gdb/test_point' sel =arcpy.SelectLayerByLocation_management(point, 'WITHIN', poly, '', 'NEW_SELECTION', 'INVERT') point_select = 'point_select' arcpy.CopyFeatures_management(sel, point_select) #tbh I'm not sure this is needed #arcpy.SelectLayerByAttribute_management(point, selection_type='CLEAR_SELECTION') if __name__ == "__main__": main()

Re: Selecting points not within polygons in arcpy

blob — Mon, 01 Jul 2024 06:35:34 GMT

This worked, thank you!

Re: Selecting points not within polygons in arcpy

blob — Mon, 01 Jul 2024 06:36:07 GMT

Good suggestion, I will implement this as well!