topic Re: How to get a count zero for arcpy.GetCount_management in Python Questions

How to get a count zero for arcpy.GetCount_management

Aнастасия88 — Wed, 09 Nov 2022 08:23:01 GMT

Hello, I am just wondering if anyone tells me the way to get a count zero to exit from the while loop that uses arcpy.GetCount_management.

I set up for loop to go through a selection of intersection between polygon (ssLyr) layer and point geometry (cenPnt). Then, while the selected polygon count is greater than zero, a second for loop is carried out. But I would like to exit the while loop in case a specific value (neigbID == 9999) is returned during the second loop.

I tried a couple of ways; arcpy.management.SelectLayerByAttribute(ssLyr, "CLEAR_SELECTION"), del cursor1, arcpy.Delete_management(ssLyr) to get zero count from int(arcpy.GetCount_management(ssLyr).getOutput(0)) but none of them worked. Thank you in advance for any python coding help!

My code is here

for row in cursor: cenPnt = row[1] arcpy.management.SelectLayerByLocation(ssLyr, 'INTERSECT', cenPnt) while int(arcpy.GetCount_management(ssLyr).getOutput(0)) > 0: with arcpy.da.SearchCursor(ssLyr, fieldName2) as cursor1: for row1 in cursor1: biorID = row1[2] neigbID = row1[3] if neigbID == 9999: print("\nError - Exit loop") #Would like to get count zero here #arcpy.management.SelectLayerByAttribute(ssLyr, "CLEAR_SELECTION") #del cursor1 #arcpy.Delete_management(ssLyr) print("Check count: ", int(arcpy.GetCount_management(ssLyr).getOutput(0)))

Re: How to get a count zero for arcpy.GetCount_management

DanPatterson — Wed, 09 Nov 2022 09:29:01 GMT

The first getcount_management needs to return a value needs to return a value when the script ends.

Re: How to get a count zero for arcpy.GetCount_management

JohannesLindner — Wed, 09 Nov 2022 09:32:43 GMT

Store the count in a variable. If you encounter your break condition, change that variable to 0 before breaking out of the for loop.

for row in cursor: cenPnt = row[1] arcpy.management.SelectLayerByLocation(ssLyr, 'INTERSECT', cenPnt) ssLyrCount = int(arcpy.GetCount_management(ssLyr).getOutput(0)) while ssLyrCount > 0: with arcpy.da.SearchCursor(ssLyr, fieldName2) as cursor1: for row1 in cursor1: biorID = row1[2] neigbID = row1[3] if neigbID == 9999: print("\nError - Exit loop") ssLyrCount = 0 break

I don't know the rest of your script, but the snippet you posted will result in an infinite while loop if you select at least 1 feature and have no features with neigbID=9999 in the selection. Any reason to use while over if?

Re: How to get a count zero for arcpy.GetCount_management

Aнастасия88 — Wed, 09 Nov 2022 22:05:59 GMT

Hi Johannes, thanks a lot for your follow up and inquiry!

The rest of scripts continues with elif to deal with a case that biorID is not equal to neighbID. This continues while the output count is one but once it gets zero, then other functions are to be triggered. I don't know if this is the best way but I wrote a code like below.

elif biorID != neighbID: Expression2 = "BID = {0}".format(neighbID) arcpy.management.SelectLayerByAttribute(ssLyr, 'NEW_SELECTION', Expression2) print('Expression2 is: ', Expression2) if ssLyrCount == 0: ##Other functions## else: pass

Re: How to get a count zero for arcpy.GetCount_management

Aнастасия88 — Wed, 09 Nov 2022 22:33:39 GMT

Hi Dan, thanks for your reply!

What I wanted is actually just keep the while loop continues in the special case.