Why is the vertical axis flipped sometimes?

[philipbaileynar]

We are calling py3DEP with geoJSON polygon boundaries and sometimes the data are returned with the vertical axis flipped. Here is an example:

https://github.com/Riverscapes/riverscapes-tools/blob/3dep/packages/rscontext/research/3dep_testing.ipynb

This only happens sometimes and we can't figure out the pattern as to why. Any advice would be appreciated!

[cheginit]

Thanks for providing the example notebook.

The issue seems to be with matplotlib, since when I plot them with xarray itself, it looks fine:

[KellyMWhitehead]

Thank you for the quick response!

I still seem to be having reversed y values when I save the array to geotiff.

I will admit I have not used xarrays much, but when I look at the y coordinates they do appear to be in reversed order between the 10m and 1.1m dems:

[cheginit]

Ah, I see what you mean. This is a known issue with xarray.merge, you can check it here.
Py3DEP, under-the-hood, decomposes large requests into smaller chunks then merge the results before returning it to the user. The 10-km resolution doesn't need any decomposition so the data is returned without any need for merging but 1-km resolution has to be decomposed and then merged which leads to this issue.
A quick fix for this case is to sort the 1-km dataset to match that of the 10-km dataset:

[cheginit]

Since the PR on xarray is still open, I will push a temporary fix for Py3DEP until the PR in xarray gets merged.

[cheginit]

@philipbaileynar and @KellyMWhitehead, thanks for opening the issue. I pushed a fix, you can either update Py3DEP using pip install --no-deps -U git+https://github.com/cheginit/py3dep to get the fix or use the sort method that I mentioned earlier until I officially release a new version (probably by the end of the next week).

[cheginit]

I addressed issue in the upstream package, PyGeoUtils, so you can install the fix by updating that package instead, i.e. pip install --no-deps -U git+https://github.com/cheginit/pygeoutils or, as I said, just sort it manually and wait for the upcoming official release.

[cheginit]

Since the issue is resolved, I will close it. Please feel free to reopen if you still have the issue.