Automating a Field Calculation Using 2 Datasets

BK710 — Fri, 18 Mar 2022 05:25:11 GMT

I'm trying to populate a field based on the output of a "Field Join" between two datasets. Specifically:

IF an item in APN_Dataset "matches" (based on Field Join tool) an item in Parcel_Datset, THEN "JoinParcelDataset" field cell = name of Parcel_Dataset (there are 71 of these datasets that I also want to iterate through with "iterate dataset" in modelbuilder)

My problem follows as such:

1. Moving the 71 datasets to a workspace in chronological order for sequential iteration (newest to oldest)

2. I do not know where to enter the SQL expression (calculate field/calculate value tool? inside of modelbuilder)

3. I only want the name of Parcel_Dataset to be assigned to the matching cell if the cell is <null>

This would be some kind of nested loop, inside one of the tools in model builder with an interator for the 71 datasets I would like to compare against a single table. Thanks for your help!

Re: Automating a Field Calculation Using 2 Datasets

JohannesLindner — Fri, 18 Mar 2022 12:02:53 GMT

Are you married to doing it with ModelBuilder? Because that seems like an easy job for Python (untested):

import os parcels = [ "path:/to/Parcel_Dataset_1", "path:/to/Parcel_Dataset_2", "path:/to/Parcel_Dataset_3", ] apn = "path:/to/APN_Dataset" # read the parcel data parcel_data = dict() for parcel in parcels: parcel_name = os.path.basename(parcel) join_field_values = [row[0] for row in arcpy.da.SearchCursor(parcel, ["JoinField"])] parcel_data[parcel_name] = join_field_values # parcel_data looks like this: #parcel_data = { # "Parcel_Dataset_1": [1, 2, 3, 4, 5, 6], # "Parcel_Dataset_2": [7, 8, 9], # "Parcel_Dataset_3": [1, 2, 5, 8, 10, 11], # } # open an UpdateCursor on APN, filter only features where TargetField is empty with arcpy.da.UpdateCursor(apn, ["JoinField", "TargetField"], "TargetField IS NULL") as cursor: # loop throguh the APN features for join_value, parcel_name in cursor: # loop through the parcel datasets for p in parcel_data: if join_value in parcel_data[p]: # there is a match in this parcel dataset parcel_name = p # stop looping through the rest of the parcel datasets break # write the parcel dataset name to the APN dataset # note: if no match was found in all of the parcel datasets, parcel_name # will be null cursor.updateRow([join_value, parcel_name])

Then the problem would be simply how to sort your parcel datasets. You can input them in the correct order manually, but if they have a date or version number or something similar in their name, you can also do it automatically

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Automating a Field Calculation Using 2 Datasets

Re: Automating a Field Calculation Using 2 Datasets