""" Problem with Numpy dtypes in a Python dict """

import numpy as np

# dict for conversion from unsigned to signed
typesDict = {np.uint8: np.int8,
             np.uint16: np.int16,
             np.uint32: np.int32,
             np.uint64: np.int64}

# array of unsigned type
aU = np.array([1, 2, 3], dtype=np.uint16)
dtypeU = aU.dtype
# make sure array is of unsigned type
assert dtypeU == np.uint16

# get the corresponding signed type
dtypeS = typesDict.get(dtypeU, None)

print("dtype: {} => {}".format(dtypeU, dtypeS))  # expected: uint16 => int16