topic Re: Can I use a Numpy Expression in the Field calculator inside PRO? in ArcGIS Pro Questions

Can I use a Numpy Expression in the Field calculator inside PRO?

mlopezr95984 — Thu, 29 Apr 2021 23:00:17 GMT

Hello,

I am trying to calculate a field in ArcGIS PRO. The field should contain a constant in every row. This constant will be equal to the maximum of another column in the table.dbf WFr_100.

I can get to the number with this code, but I would like to do it through the field calculator inside Arcgis PRO. Is there a way to do that?

# Import system modules

import arcpy

import numpy

# Set environment settings

arcpy.env.workspace = r"C:\Users\MD \Documents\ArcGIS\Projects\IP\Default.gdb"

input = "WFr_100" arr = arcpy.da.TableToNumPyArray(input, ('CMass'))

x=(arr["CMass"].max())

print(x)

Re: Can I use a Numpy Expression in the Field calculator inside PRO?

DanPatterson — Fri, 30 Apr 2021 01:34:57 GMT

Do the work outside and bring it back in.

Close Pro to make sure any file locks are gone.

Verbose example

from arcpy.da import TableToNumPyArray, ExtendTable tbl = r"C:\arcpro_npg\npg\Project_npg\npgeom.gdb\sample_10k" # my table arr = TableToNumPyArray(tbl, ["OID@", "Age"]) # the objectid field and another arr1 = arr["OID@"] # make oid values arr2 = arr["Age"] # Get the values you are interested count = arr2.shape[0] # get the length of the array mx = np.nanmax(arr2) # ---- now get the max... nanmax accounts for nulls vals = np.repeat(mx, count) # ---- repeat the maximum "count" times # create output ---- excitement builds z = np.empty_like(arr) # build the output array z.dtype.names = ("OID@", 'Max_Vals') # make your output names z["OID@"] = arr1 # put the id values in z['Max_Vals'] = vals # put the max in ExtendTable(tbl, "OID@", z, "OID@") # magic-orama ... like a join

Now open Pro and open the table to see the results.

I have helper functions that expedite this, but you need to understand the procedure first.

numpy is extremely powerful and I have numerous blogs on its use with arcpy in the Python Blogs... look for me and me before retirement.

Re: Can I use a Numpy Expression in the Field calculator inside PRO?

mlopezr95984 — Fri, 30 Apr 2021 20:07:10 GMT

Spot on, Dan! Thank you.