topic ModelBuilder - automatic rename attributes in table in ArcMap Questions

ModelBuilder - automatic rename attributes in table

StanislavaV — Sat, 20 Mar 2021 15:20:32 GMT

Hi,

I have another question for today - automatic renaming values in ModelBuilder?

My table have attributes looks like this:

FID CODE CODE2

1 1001 1

2 1001 1

3 2000 1

4 2000 1

5 2000 1

...........and so on.

And my goal is - that column CODE2 will be automatically calculated.

So, there are two polygons with CODE 1001 but CODE2 is different for each of these.

FID CODE CODE2

1 1001 1

2 1001 2

3 2000 1

4 2000 2

5 2000 3

.....

Is there some possibility to do this?

Thank you.

Re: ModelBuilder - automatic rename attributes in table

DavidPike — Sat, 20 Mar 2021 18:21:35 GMT

I would suggest a Python field calculation. I've never come across anything to automatically do something like that.

If your data is ordered by FID, will it always be ordered by CODE? i.e. will it always follow the logical structure you provided in the example?

FID CODE CODE2

1 1001 1

2 1001 2

3 2000 1

4 1001 3

5 2000 2

If not, is the order of assignment of auto-incremented values important? i.e. would you be happy if the lowest FID had the highest increment or that it was random?

FID CODE CODE2

1 1001 2

2 1001 1

3 2000 3

4 2000 1

5 2000 2

Re: ModelBuilder - automatic rename attributes in table

StanislavaV — Sat, 20 Mar 2021 18:33:08 GMT

Yes, it does not really matter. That CODE2 is just needed for differentiate polygons with label CODE.

Re: ModelBuilder - automatic rename attributes in table

DavidPike — Sat, 20 Mar 2021 18:56:43 GMT

OK, so run a field calculator ensuring that Python is chosen as the expression type.

pre-logic script code/ Code block:

CODE_dict = {} def auto_increment(field): global CODE_dict if field in CODE_dict.keys(): CODE_dict[field] += 1 return CODE_dict[field] else: CODE_dict[field] = 1 return 1

to run it using that function:

auto_increment(!CODE!)

The code block creates a global dictionary to store a key of the CODE against an increment. If no key exists in the dictionary, the key(CODE) is added to it, with a value of 1. This is also then returned by the function.

If the key(CODE) does exist in the dictionary, the value is then incremented by 1, and that value returned.

Re: ModelBuilder - automatic rename attributes in table

StanislavaV — Sat, 20 Mar 2021 19:58:36 GMT

yay!

that´s exactly what I was looking for the whole day 🙂 thank you.