numpy.float64 转换 python float

numpy.float32 -> "python float"
numpy.float64  python float

import numpy as np
# examples using a.item()
type(np.float32(0).item()) # <type "float">
type(np.float64(0).item()) # <type "float">
type(np.uint32(0).item())  # <type "long">
# examples using np.asscalar(a)
type(np.asscalar(np.int16(0)))   # <type "int">
type(np.asscalar(np.cfloat(0)))  # <type "complex">
type(np.asscalar(np.datetime64(0)))  # <type "datetime.datetime">
type(np.asscalar(np.timedelta64(0))) # <type "datetime.timedelta">