topic Re: Field calculator returns null fields? in Geoprocessing Questions

Field calculator returns null fields?

ShelbyZemken1 — Sat, 02 Jan 2016 13:23:48 GMT

I'm using the field calculator to reclassify a raster table. My goal is to reclassify all negative values to zero, and keep all other original values. See attached photo.

I'm running the following block of code:

def Reclass(corrected_value):

if Value <= 0:

return 0

elif Value >= 1:

return Value

followed by:

Reclass( !corrected_value!)

Executing the code returns no errors, but values remain as NULL after processing. What gives?

Re: Field calculator returns null fields?

DanPatterson_Retired — Sat, 11 Dec 2021 07:41:15 GMT

def Reclass(value):
    if value <= 0:
        return 0
    elif value >=1:
        return value

Reclass(!Value!)

But I suspect you really want to reclass the Value field

Re: Field calculator returns null fields?

ShelbyZemken1 — Sat, 02 Jan 2016 18:51:38 GMT

Dan, thanks for your quick response. You're absolutely right, I need to reclassify a raster. Unfortunately the values are incorrect in the raster. For some reason there are some random values from -32000 to 0.

Can I reclassify all negative values as -1 and then have a raster values from 0-3460?

Re: Field calculator returns null fields?

DanPatterson_Retired — Sat, 02 Jan 2016 19:10:58 GMT

That value is your nodata value for an integer raster, I would just leave it alone. Since you aren't reclassifying the raster, but just reclassing values in a table, then just remember that and leave well enough alone

Re: Field calculator returns null fields?

ShelbyZemken1 — Sat, 02 Jan 2016 19:44:31 GMT

thanks for your patience Dan