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creare-com / pydem

Python library for Global Hydrology Analysis. Used to calculate upstream contributing area, aspect, slope, and topographic wetness index.
Apache License 2.0
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Type casting problems with SRTM DEM #5

Closed mbjoseph closed 7 years ago

mbjoseph commented 7 years ago

I was hoping to compute slope and aspect for some digital elevation models from the NASA SRTM mission, and ran into a type error that seems to be related to the _find_flats_edges function.

Here's a reproducible example Jupyter notebook that demonstrates the problem: https://gist.github.com/mbjoseph/9934454330b5715db9529502cf415f72#file-pydem-srtm-example-ipynb

A TypeError is raised: 

TypeError: Cannot cast ufunc add output from dtype('float64') to dtype('bool') with casting rule 'same_kind'

It seems like similar issues have arisen elsewhere, e.g., https://github.com/numpy/numpy/issues/7225

mpu-creare commented 7 years ago

@mbjoseph I'll have a look later today. I'd rather not intentionally cast unsafely, I'll see if there's another fix.

Thanks for finding this! I haven't kept up with changes in numpy -- evidently. Are you up and running at least? Are you on a windows machine?

mpu-creare commented 7 years ago

@mbjoseph could you try the proposed fix in 311d2171f07ce1fe0955bff194bde573ec1e3d42 ? It's on the develop branch.

mbjoseph commented 7 years ago

Your fix with 311d217 worked beautifully, thanks! Also I was able to replicate this on OSX and Ubuntu - I haven't tried on a Windows machine.

mpu-creare commented 7 years ago

Excellent, I'll push it into master for the next release.