:class:`cupy.ndarray` is the CuPy counterpart of NumPy :class:`numpy.ndarray`. It provides an intuitive interface for a fixed-size multidimensional array which resides in a CUDA device.
For the basic concept of ndarrays, please refer to the NumPy documentation.
.. autosummary:: :toctree: generated/ :nosignatures: cupy.ndarray
:class:`cupy.ndarray` is designed to be interchangeable with :class:`numpy.ndarray` in terms of code compatibility as much as possible. But occasionally, you will need to know whether the arrays you're handling are :class:`cupy.ndarray` or :class:`numpy.ndarray`. One example is when invoking module-level functions such as :func:`cupy.sum` or :func:`numpy.sum`. In such situations, :func:`cupy.get_array_module` can be used.
.. autosummary:: :toctree: generated/ :nosignatures: cupy.get_array_module cupyx.scipy.get_array_module
:class:`cupy.ndarray` and :class:`numpy.ndarray` are not implicitly convertible to each other. That means, NumPy functions cannot take :class:`cupy.ndarray`s as inputs, and vice versa.
- To convert :class:`numpy.ndarray` to :class:`cupy.ndarray`, use :func:`cupy.array` or :func:`cupy.asarray`.
- To convert :class:`cupy.ndarray` to :class:`numpy.ndarray`, use :func:`cupy.asnumpy` or :meth:`cupy.ndarray.get`.
Note that converting between :class:`cupy.ndarray` and :class:`numpy.ndarray` incurs data transfer between the host (CPU) device and the GPU device, which is costly in terms of performance.
.. autosummary:: :toctree: generated/ :nosignatures: cupy.array cupy.asarray cupy.asnumpy