topic Re: Python Toolbox Issues: using ArcPy Select by Location in Python Questions

Python Toolbox Issues: using ArcPy Select by Location

DPG — Wed, 18 May 2022 22:31:48 GMT

Hi there. I am fairly new to Python and I am struggling to get my first Python Toolbox to work.

The purpose of the tool is to create a fishnet over a set area, before selecting cells within the fishnet that intersect a boundary shapefile. Cells that do not intersect the boundary are deleted. See this example below which uses the UK:

The boundary shapefile has been set up to be a selectable parameter inside the tool. My current script looks like this:

# -*- coding: utf-8 -*- import arcpy class Toolbox(object): def __init__(self): self.label = "Toolbox" self.alias = "toolbox" # List of tool classes associated with this toolbox self.tools = [Tool] class Tool(object): def __init__(self): self.label = "Tool" self.description = "" self.canRunInBackground = False def getParameterInfo(self): # Param 0 = UK Boundary param0 = arcpy.Parameter( displayName="Input Feature Class", name="Parameter0", datatype="GPFeatureLayer", parameterType="Required", direction="Input") param0.filter.list=["POLYGON"] params = [param0] return params def isLicensed(self): return True def updateParameters(self, parameters): return def updateMessages(self, parameters): return def execute(self, parameters, messages): # Overwrite existing file of the same name arcpy.env.overwriteOutput = True # Reference Parameters input1 = parameters[0].valueAsText arcpy.management.CreateFishnet( "UKFishNet", "-13.6913900375366 49.8654174804687", "-13.6913900375366 59.8654174804687", 1, 1, None, None, "1.76416802406319 61.527084350586", "NO_LABELS", "-13.6913900375366 49.8654174804687 1.76416802406319 61.527084350586", "POLYGON") arcpy.management.SelectLayerByLocation( "UKFishNet", "INTERSECT", input1, None, "NEW_SELECTION", "INVERT") arcpy.management.DeleteRows("UKFishNet") return

However, when I run the script - although I get no errors - I simply get an empty shapefile ("UKFishNet") sent to my geodatabase. Can anybody provide some guidance on what I'm doing wrong? Any pointers would be very much appreciated!

Re: Python Toolbox Issues: using ArcPy Select by Location

AlfredBaldenweck — Wed, 18 May 2022 21:57:44 GMT

Oh weird.

My guess is that it's not honoring the selection by Location when you run Delete Rows.

Maybe try setting the select by Location as a new variable, and passing that variable into DeleteRows?

FishSelect= arcpy.management.SelectLayerByLocation("yadda yadda yadda") arcpy.management.DeleteRows(FishSelect)

Re: Python Toolbox Issues: using ArcPy Select by Location

John_S — Wed, 18 May 2022 22:01:55 GMT

I'm not in a position to test out your specific code at the moment and I'm not personally that familiar with the CreateFishnet tool, but just from a brief review, it looks like CreateFishnet outputs a feature class. You are then trying to use that feature class as the input to SelectLayerByLocation. However, SelectLayerByLocation does not actually allow feature classes as an input, only layers (of feature classes). So, while there may or may not be other problems causing the issue, at the very least you should consider adding Make Feature Layer tool (https://pro.arcgis.com/en/pro-app/2.8/tool-reference/data-management/make-feature-layer.htm) before SelectLayerByLocation. And use that newly created layer as the input to SelectLayerByLocation and DeleteRows. Then, to keep from having a bunch of temporary layers in memory (which can cause issues if you have multiple layers with the same exact name), I would add Delete tool (https://pro.arcgis.com/en/pro-app/2.8/tool-reference/data-management/delete.htm) after DeleteRows to delete the temporarily created layer.

Re: Python Toolbox Issues: using ArcPy Select by Location

DPG — Wed, 18 May 2022 22:28:17 GMT

Thank you! I added this right after creating the fishnet and it worked like a treat:

arcpy.management.MakeFeatureLayer("UKFishNet", "UKFishNet_lyr") arcpy.management.SelectLayerByLocation( "UKFishNet_lyr", "INTERSECT", input1, None, "NEW_SELECTION", "INVERT") arcpy.management.DeleteRows("UKFishNet_lyr") return