added image to docs explaining drop_axis option of map_blocks()

[ParticularMiner]

• Closes Unwanted aggregation map_blocks #8830
• Tests added / passed
• Passes pre-commit run --all-files

Does this image help to clarify the docs on the drop_axis option of map_blocks()?

[jsignell]

Thanks for opening this @ParticularMiner! I actually think this behavior is undesirable, so I'm going to see if I can get it working more how I expect, but this is definitely how it works now so we should still merge this in the meantime. It looks like the docs is not rendering quite right though - probably needs some whitespace. You can see the preview here: https://dask--8868.org.readthedocs.build/en/8868/generated/dask.array.map_blocks.html

[ParticularMiner]

Many thanks for that link @jsignell ! Just what I was looking for!

I'm still struggling to find the correct code to embed the image in the docstring, though. Any idea on how to do that?

Regarding the expected behavior of map_blocks(..., drop_axis=x), I've just noticed the following comments in the source code of map_blocks() itself:

dask/dask/array/core.py

Lines 869 to 872 in e49880b

	if drop_axis:
	# We concatenate along dropped axes, so we need to treat them
	# as if there is only a single chunk.
	starts[i] = [

Moreover, there seem to be other functions and tests in dask that depend on or test this behavior.

[ParticularMiner]

I finally succeeded in embedding the image! 🎉

It turned out that I needed to use an absolute file path rather than a relative file path to the image file.

You can see the preview (same link as above) here:
https://dask--8868.org.readthedocs.build/en/8868/generated/dask.array.map_blocks.html

[jsignell]

Thanks for persevering!