topic Re: Calculate Z Values Using CalculateField_management in Geoprocessing Questions

Calculate Z Values Using CalculateField_management

Jasonvan_Warmerdam — Mon, 13 Aug 2012 18:32:34 GMT

Hi,

I'm wanting to calculate Z values from a PointZM shapefile that I created using the 3D analyst extension InterpolateShape. I know that you can just right click from within Arc and calculate the geometry using the z value but I wanted to do this using geoprocessing.

Currently I've got:

arcpy.CalculateField_management([InputPointZ], "METERS", "!shape.Z!", "PYTHON_9.3", "")

I don't know what the proper syntax for calculating the Z value and I'm assuming it's something like

"!shape.Z!"

, but that's not it. Anyone been able to do this with the CalculateField_management tool?

Re: Calculate Z Values Using CalculateField_management

JasonScheirer — Sun, 12 Dec 2021 05:36:20 GMT

Basically your approach isn't going to work exactly, as you have to alter the row's geometry object.

Going to need to set !shape!.Z here, so maybe do it as a side effect of calculating some other field. For example, an expression of

CalcZ(!METERS!, !shape!)

and a codeblock of

def CalcZ(meter_length, shapeval):
    shapeval.Z = 100
    return meter_length

This would recalculate METERS to itself and as a side effect change the Z value to 100. Though this all feels like a somewhat indirect approach, you are likely much better off in just writing a short python script with an UpdateCursor as it'd be a lot more coherent and not many more lines of code.

cur = arcpy.UpdateCursor(InputPointZ) 
for row in cur:
    row.shape.Z = 100
    rows.updateRow(row)

del row, cur

Re: Calculate Z Values Using CalculateField_management

EricRice — Mon, 13 Aug 2012 21:40:21 GMT

Jason W.

Have you considered running the Add XY Coordinates tool? If the input is Z aware it will return the Z value from the Shape field as an output attribute.

Best,
Eric