topic Re: Dissolve/ based on condition in Geoprocessing Questions

Dissolve/ based on condition

HushamMohamed — Wed, 19 Feb 2020 06:33:39 GMT

Hello,

I would like to dissolve large polygon feature data set(25000 units) based on 2 conditions:

1- by attribute value partially matched, (UNIT field)

for example

id	Unit
1	CLAY BROWN UNIT 2
2	CLAY BROWN UNIT 3
3	CLAY BROWN UNIT 4 sub unit 6
4	CLAY BROWN UNIT 5

2- only adjacent polygon should be dissolved. ( warning topology is not clean 100% , small gaps may appear)

example only rows 1,2,3 are adjacent polygon.

I would appreciate any suggestion.

Thank you

Re: Dissolve/ based on condition

DavidPike — Wed, 19 Feb 2020 08:51:29 GMT

Hi,

The dissolve will only dissolve adjacent features so condition 2 will be met anyway.

Regards gaps I would look at the integrate tool but be warned this will alter the existing data. I highly recommend making a copy before u do anything with it. It will also probably destroy and topology u have set up.

If u mean a partial field match I would probably add a new field such as higher level soil unit etc. And run a field calculator with a python code block to get the matches. I can write this when I get some time

Re: Dissolve/ based on condition

HushamMohamed — Wed, 19 Feb 2020 09:06:57 GMT

Thank for your your helpful information,

The dissolve will only dissolve adjacent features so condition 2 will be met anyway.

Yes I mean partial field match, from the example table (Clay Brown Unit) is partial match. another Example

1- East Soil corrected 6th addition

2- East Soil corrected 5th addition

3- East Soil corrected 5th sub plat

only 1,2 should be dissolved.

I would love to get that python script, to test,

Thank you.

Re: Dissolve/ based on condition

HushamMohamed — Wed, 19 Feb 2020 09:16:14 GMT

defining multiple flags in code block is a challenge, do I need to use regex.

Re: Dissolve/ based on condition

DavidPike — Wed, 19 Feb 2020 11:31:45 GMT

How many entries are there to match to? If you list them I'll put them in the code to match. If theres hundreds I'll think of a better solution

Re: Dissolve/ based on condition

HushamMohamed — Wed, 19 Feb 2020 14:21:56 GMT

Thanks, I am afraid they are hundreds. I have 25000 records, (10 feature classes).

Re: Dissolve/ based on condition

DavidPike — Wed, 19 Feb 2020 14:34:40 GMT

Is there an identifiable pattern to break/group the string by? If not I cant really see a solution.

Re: Dissolve/ based on condition

HushamMohamed — Wed, 19 Feb 2020 15:00:33 GMT

Yes that is the problem, there is no identifiable pattern,

Thank you very much.

Re: Dissolve/ based on condition

DanPatterson_Retired — Fri, 10 Dec 2021 23:33:10 GMT

If there is no pattern, you may have to break them into groups and process accordingly. Sometimes there is no one-solves-all. You indicate that you have 10 featureclasses but 25000 records. It appears you are looking for a substring within a string. If it were you could use that information to parse the data first prior to determining whether to dissolve.

cases = ['East Soil corrected 6th addition',
         'East Soil corrected 5th addition',
         'East Soil corrected 5th sub plat']

for c in cases:
    if 'East Soil corrected' in c and 'addition' in c:
        print("dissolve")
    else:
        print("don't dissolve")
        
dissolve
dissolve
don't dissolve‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Dissolve/ based on condition

HushamMohamed — Wed, 19 Feb 2020 15:50:01 GMT

Thank you, using Case statement is not an option, keeping up with it for anything new may be a pain.