topic Re: Error when doing basic calculate field command: ArcGISPro in Ohio GIS Questions

Error when doing basic calculate field command: ArcGISPro

MasonGrant — Mon, 23 Apr 2018 01:37:23 GMT

I get this error when trying to calculate a field:

ERROR 000539: Error running expression: u"5359" / 5312094.0
Traceback (most recent call last):
File "<expression>", line 1, in <module>
TypeError: unsupported operand type(s) for /: 'str' and 'float'
Failed to execute (CalculateField).

I downloaded census tracts for a county in Ohio, then I joined thiswith population data from American Fact Finder. After I export the data I joined, I add a new field "Pop Density"... To calculate this new field I need to divide Total population "HD01_S001" with the area of the Census tract "ALAND".. When I put this expression in the calculate field command I get the error above.. Don't understand what could be going wrong here...

Re: Error when doing basic calculate field command: ArcGISPro

TiffanyRufo — Mon, 23 Apr 2018 11:16:50 GMT

Hello! By my best understanding the division is not working because the field types are not the same. Somehow you need to get the population density from a string to a float.

I don't know of an elegant way to do this, you could brute force it by creating a new field make the type double and run a quick calculation so that the new field equals the values of "HD01_S001". After that is done you should be able to do your original calculation with the new field substituting for the population density field.

Hope someone has a more finessed solution for you!

Re: Error when doing basic calculate field command: ArcGISPro

BeckyGerlach — Mon, 23 Apr 2018 11:45:46 GMT

For Python you should be able to

float(!HD01_S001!)/float(!ALAND!)