topic Re: Field Calc Sequential Number based on another column in Geoprocessing Questions

Field Calc Sequential Number based on another column

BrandenHarding — Tue, 13 Oct 2020 14:50:24 GMT

I need to populate a column (Level4Code) with the field calculator that counts sequentially based on another column (Level3Name) and includes 4 digits. Here is an example of a table that's already populated correctly:

Level3Name	Level4Code
Adilabad	0001
Adilabad	0002
Adilabad	0003
Agar Malwa	0001
Agar Malwa	0002
Agra	0001
Agra	0002

The out of the box sequential code does not do it correctly since it doesn't loop based on any other column.

So far, I've tried this code snippet to count but I am not getting the results I need. This only seems to count the total number of times that word in Level3Name is present:

dict = {} # make a dictionary
def myFunc(myClass): # this is the function
global dict # specify global
dict[myClass] = dict.get(myClass, 0) + 1 # if the dictionary key for the value exists, add 1 to it. If not, make it 0.
return dict[myClass] # return the value for that key

Any suggestions? I am new to Python so any help would be great.

Re: Field Calc Sequential Number based on another column

BrandenHarding — Tue, 13 Oct 2020 20:23:05 GMT

Update: Using this python script I was able to have it count properly and populate the needed column. I guess now I just need to know how to set it to have 4 digits with leading 0's (ie 0001 instead of 1, or 0110 instead of 110). Any suggestions?

tbl = r'C:\my\data.gdb\table'

data_dict = defaultdict(int)

with arcpy.da.UpdateCursor(tbl, ["Level3Name", "Level4Code"]) as cur:

for uniq, code in cur:

data_dict[uniq] += 1

cur.updateRow([uniq, data_dict[uniq]])

Re: Field Calc Sequential Number based on another column

JoshuaBixby — Wed, 18 Nov 2020 18:06:08 GMT

As you have learned, or maybe just coincidentally avoided, using Field Calculator for creating sequential numbering runs into problems if the sequencing doesn't line up with the ObjectID sequence.

Regarding your follow-up question, do you want to have the data stored as "000x" etc... or do you just want the formatting for a table you are looking at to be that way? If the former, you need Level4Code to be a string field and use string formatting. If the latter, you can create a custom number formatting for that field in the table in Pro.

The following should work for string formatting:

cur.updateRow([uniq, "{:0>4}".format(data_dict[uniq])])