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raster_map errors on valid combinations of dtype and nodata value #358

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emlys opened this issue Nov 2, 2023 · 1 comment · May be fixed by #408
Open

raster_map errors on valid combinations of dtype and nodata value #358

emlys opened this issue Nov 2, 2023 · 1 comment · May be fixed by #408
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bug Something isn't working
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2.4.7

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@emlys
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emlys commented Nov 2, 2023

If target_dtype and target_nodata are provided to raster_map, it tries to confirm that the nodata value fits into the dtype using numpy.can_cast. This does not work as I expected:

>>> float32_min = float(numpy.finfo(numpy.float32).min)
>>> numpy.can_cast(float32_min, numpy.float32)
False

It's usually not necessary to set the target_dtype and target_nodata, but this bug prevents us from doing so in some cases.
@emlys emlys added the bug Something isn't working label Nov 2, 2023
@dcdenu4
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dcdenu4 commented Nov 6, 2023

Interesting. This looks like an issue with casting to float.

>>> numpy.can_cast(numpy.finfo(numpy.float32).min, numpy.float32)
True
>>> numpy.can_cast(float(numpy.finfo(numpy.float32).min), numpy.float32)
False
>>> numpy.can_cast(float(numpy.finfo(numpy.float32).min), numpy.float64)
True

So casting with float is returning a float64 type!

Using casting=same_kind works though.

>>> numpy.can_cast(float(numpy.finfo(numpy.float32).min), numpy.float32, "same_kind")
True

‘same_kind’ means only safe casts or casts within a kind, like float64 to float32, are allowed.

phargogh added a commit to phargogh/pygeoprocessing that referenced this issue Oct 10, 2024
@phargogh
Writing a test to exercise the known error case.
c5524d4 
RE:natcap#358
phargogh added a commit to phargogh/pygeoprocessing that referenced this issue Oct 10, 2024
@phargogh
Allowing casting within the same kind of dtype. RE:natcap#358
a7de3a7
phargogh added a commit to phargogh/pygeoprocessing that referenced this issue Oct 10, 2024
@phargogh
Adding note to history. RE:natcap#358
eee8919
@phargogh phargogh linked a pull request Oct 10, 2024 that will close this issue
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@phargogh phargogh modified the milestones: 2.4.6, 2.4.7 Oct 11, 2024
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Handle raster_map case with float32 array and float64 nodata values phargogh/pygeoprocessing
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@dcdenu4 @phargogh @emlys