[tests][python] Handle data types more accurate in C API test #4297
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StrikerRUS
requested review from
btrotta,
chivee,
guolinke and
shiyu1994
as code owners
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Looks good! Thanks very much for breaking long lines like into one-argument-per-line. I think that makes it easier to read, which is really important since some of the functions take so many positional arguments.
I just left one question about how we're using ctypes but it isn't directly related to this PR and could be addressed in a later PR if something needs to change.
| c_array(ctypes.c_int, csr.indices), | ||
| csr.data.ctypes.data_as(ctypes.POINTER(ctypes.c_void_p)), | ||
| dtype_float64, | ||
| csr.indptr.ctypes.data_as(ctypes.POINTER(ctypes.c_int32)), |
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could this use .byref() instead of POINTER()?
From https://docs.python.org/3/library/ctypes.html#passing-pointers-or-passing-parameters-by-reference
ctypes exports the
byref()function which is used to pass parameters by reference. The same effect can be achieved with thepointer()function, although pointer() does a lot more work since it constructs a real pointer object, so it is faster to usebyref()if you don’t need the pointer object in Python itself.
I'm very unfamiliar with ctypes so apologies if that doesn't make sense.
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I wish I knew... The cited paragraph looks like we can benefit from using byref instead of pointer. I will create a new issue for this idea to not lose in the merged PR and read about it.
| label = np.array(label, dtype=np.float32) | ||
| csr = sparse.csc_matrix(mat) | ||
| csc = sparse.csc_matrix(mat) |
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thanks for catching this!
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This pull request has been automatically locked since there has not been any recent activity since it was closed. To start a new related discussion, open a new issue at https://github.com/microsoft/LightGBM/issues including a reference to this. |
Linking #4292.
Match function signatures from https://github.com/microsoft/LightGBM/blob/master/include/LightGBM/c_api.h.