nptyping

Type hints for Numpy!

Installation

pip install nptyping

Usage

NDArray

nptyping.NDArray lets you define the shape and type of your numpy.ndarray.

You can:

• specify the number of dimensions;
• specify the size per dimension;
• specify the type of the array;
• instance check your array with your nptying type.

Examples

An Array with any dimensions of any size and any type:

>>> from nptyping import NDArray
>>> from typing import Any


>>> NDArray
NDArray[(typing.Any, ...), typing.Any]

>>> NDArray[(Any, ...)]
NDArray[(typing.Any, ...), typing.Any]

>>> NDArray[(Any, ...), Any]
NDArray[(typing.Any, ...), typing.Any]

An array with 1 dimension of any size and any type:

>>> NDArray[Any]
NDArray[(typing.Any,), typing.Any]

>>> NDArray[(Any,)]
NDArray[(typing.Any,), typing.Any]

>>> NDArray[Any, Any]
NDArray[(typing.Any,), typing.Any]

>>> NDArray[(Any,), Any]
NDArray[(typing.Any,), typing.Any]

An array with 1 dimension of size 3 and any type:

>>> NDArray[3]
NDArray[(3,), typing.Any]

>>> NDArray[(3,)]
NDArray[(3,), typing.Any]

>>> NDArray[(3,), Any]
NDArray[(3,), typing.Any]

An array with 3 dimensions of size 3, 3 and any and any type:

>>> NDArray[3, 3, Any]
NDArray[(3, 3, typing.Any), typing.Any]

>>> NDArray[(3, 3, Any)]
NDArray[(3, 3, typing.Any), typing.Any]

>>> NDArray[(3, 3, Any), Any]
NDArray[(3, 3, typing.Any), typing.Any]

An array with any dimensions of any size and type int:

>>> NDArray[int]
NDArray[(typing.Any, ...), int]

>>> NDArray[(Any, ...), int]
NDArray[(typing.Any, ...), int]

An array with 1 dimension of size 3 and type int:

>>> NDArray[3, int]
NDArray[(3,), int]

>>> NDArray[(3,), int]
NDArray[(3,), int]

An array with any dimensions of size 3 and type int:

>>> NDArray[(3, ...), int]
NDArray[(3, ...), int]

An array with 3 dimensions of sizes 3, 3, 5 and type int:

>>> NDArray[(3, 3, 5), int]
NDArray[(3, 3, 5), int]

Checking your instances

You can use NDArray with isinstance to dynamically check your arrays.

>>> import numpy as np

>>> arr = np.array([[1, 2, 3],
...                 [4, 5, 6]])

>>> isinstance(arr, NDArray[(2, 3), int])
True
>>> isinstance(arr, NDArray[(2, 3), float])
False
>>> isinstance(arr, NDArray[(2, 3, 1), int])
False

Finding the right annotation

You can use NDArray to find the type of a numpy array for you using NDArray.type_of:

>>> NDArray.type_of(np.array([[1, 2], [3, 4.0]]))
NDArray[(2, 2), float64]

py_type

With py_type you can get the Python builtin type that corresponds to a Numpy dtype:

>>> from nptyping import py_type

>>> py_type(np.int32)
<class 'int'>