I'm confused, where's the string in my Python code when I calculate this field in ArcGIS Pro?

Question

I am trying to give polygons values in a layer based on the sum population within other adjacent polygons. The polygons are adjacent as I have already sorted them through the appropriate field. This is my code:

def CreatePolls(DB_ID, pop):
    for i in DB_ID:
        SumPop = 0
        PollCount = 1        
        SumPop += pop
        if SumPop < 500:
            return PollCount
        elif SumPop > 500:
            return PollCount
            PollCount += 1
            SumPop = 0
arcpy.CalculateField_management('DB_Test', 'Poll_Div', CreatePolls("!DB_ID!","!Population!"))

When I try to run it I get the following errors:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "<string>", line 5, in CreatePolls
TypeError: unsupported operand type(s) for +=: 'int' and 'str'

Any ideas?

Answer 1

As your SumPop variable =0, we know with certainty this is an int. Your pop variable is whatever your !Population! field is. Based on the error, this field appears to be a str

You'll need to verify in your data that your Population field is actually a float or double. Alternatively, you can try to cheat and cast the field as an int. I say cheat because if you have actual string values in here, like "a", this won't work.

SumPop += int(pop)