topic Re: Singlepart to Multipart in Python Questions

Singlepart to Multipart

FinbarGillen — Sat, 01 May 2021 10:53:38 GMT

Hi,

I have a dataset of polygons.. a large quantity of these share a common ID.

The goal is to have a final dataset with one row per ID but also preserve the polygon boundaries (dissolve tool will not work in this case).

Was looking for singlepart to multipart tool where I could group by an ID field but can't find any... has anyone done this in ArcPy and would be willing to share their code? If there is a tool that I have missed even better.

Thanks!

Re: Singlepart to Multipart

JayantaPoddar — Sat, 01 May 2021 12:37:55 GMT

Polygons having common end vertices, when dissolved, will get their boundaries merged for a single-feature.

That said, check if the following workaround works for you (Be careful: This workflow will contain induced errors).

Step-1: Create a negative buffer

Step-2:

Use Dissolve on the buffered polygon FC.

On a smaller scale, the dissolved/ buffered polygon looks fine.

But when zoomed into the boundary (1:10 here), you can see the gaps.

N.B.: Use these steps at your own discretion 😉

Re: Singlepart to Multipart

DavidPike — Sat, 01 May 2021 12:42:01 GMT

Multipart polygons cannot share edges. IMHO the method Jayanta describes is the only pragmatic approach to this.

Re: Singlepart to Multipart

FinbarGillen — Tue, 04 May 2021 22:04:33 GMT

Thanks for the reply guys! Will use the accepted solution above for now!