[英]Can np.ndarray be annotated with a custom dtype?
We can create custom dtypes with record-like properties:我们可以创建具有类似记录属性的自定义数据类型:
dt = np.dtype([('R','u1'), ('G','u1'), ('B','u1'), ('A','u1')])
We can annotate the data type of an ndarray for type hinting:我们可以为类型提示注释 ndarray 的数据类型:
numpy.typing.NDArray = numpy.ndarray[typing.Any, numpy.dtype[+ScalarType]]
However, I can't work out how to hint that an array is supposed to have a custom dtype, for instance a: NDArray[dt]
results in Pylance complaining:但是,我无法弄清楚如何暗示数组应该具有自定义 dtype,例如a: NDArray[dt]
导致 Pylance 抱怨:
Declared return type, "ndarray[Any, dtype[Unknown]]", is partially unknown Pylance(reportUnknownVariableType)
Illegal type annotation: variable not allowed unless it is a type alias Pylance(reportGeneralTypeIssues)
I guess what I'm asking is if is possible to create a type from a dtype object, or what the +ScalarType means in numpy.ndarray[typing.Any, numpy.dtype[+ScalarType]]
.我想我要问的是是否可以从 dtype object 创建类型,或者 +ScalarType 在numpy.ndarray[typing.Any, numpy.dtype[+ScalarType]]
中的含义。
An array with a compound dtype like this:具有复合 dtype 的数组,如下所示:
In [98]: dt = np.dtype([('R','u1'), ('G','u1'), ('B','u1'), ('A','u1')])
In [99]: arr = np.ones(3, dt)
In [100]: arr
Out[100]:
array([(1, 1, 1, 1), (1, 1, 1, 1), (1, 1, 1, 1)],
dtype=[('R', 'u1'), ('G', 'u1'), ('B', 'u1'), ('A', 'u1')])
The elements of this array of type, np.void
这个类型数组的元素, np.void
In [101]: type(arr[0])
Out[101]: numpy.void
In [102]: arr.dtype
Out[102]: dtype([('R', 'u1'), ('G', 'u1'), ('B', 'u1'), ('A', 'u1')])
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