r.clump: added tests for r.clump module

[Shreshth-Malik]

This PR introduces pytest-based tests for the r.clump module to validate its functionality. The tests cover:

Basic Functionality: Verifies that r.clump correctly identifies clumped regions in a raster map.
Diagonal Connectivity: Tests the -d flag for identifying clumps with diagonal connectivity.

The tests use temporary regions and custom raster maps.

[petrasovaa]

r.category has json output, you can use parse_command to get the list

[petrasovaa]

because r.category already has format option, the call is more complicated:

import json
gs.parse_command("r.category", map="clumped_map", output_format="json", parse=(json.loads, {}))

[petrasovaa]

This still needs to be done.

[petrasovaa]

Please also add test for minsize and threshold

[Shreshth-Malik]

@petrasovaa I was trying to test the threshold functionality with cells values 5 and 5.5 and keeping the threshold 0.6. From my understanding if the absolute difference the cell values is <=threshold value then it clumps them together, but in my case it is not doing so. Is my understanding wrong?

My map layout looks something like:
5 5.5 NULL
NULL 5 NULL
NULL 5.5 5.5

[echoix]

The error here, now that the test is actually picked up, has to do that a grass session wasn't set. Try to look at with gs.setup.init(project, env=os.environ.copy()) as session:, that you even used in one of your other PRs here: #4755. It should do the trick. Otherwise, if the env from the session can't be passed and is really needed, use the workaround I explained in #4784

[petrasovaa]

@petrasovaa I was trying to test the threshold functionality with cells values 5 and 5.5 and keeping the threshold 0.6. From my understanding if the absolute difference the cell values is <=threshold value then it clumps them together, but in my case it is not doing so. Is my understanding wrong?

My map layout looks something like: 5 5.5 NULL NULL 5 NULL NULL 5.5 5.5

It's more complicated, it uses some normalization, see r.clump documentation. It's computed here. Something like (diff/range)^2 must be greater than threshold^2