versions/master/api/python/docs/_sources/api/legacy/ndarray/index.rst

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mxnet.ndarray
=============

The NDArray library in Apache MXNet defines the core data structure for all mathematical computations. NDArray supports fast execution on a wide range of hardware configurations and automatically parallelizes multiple operations across the available hardware.

Example
-------

The following example shows how you can create an NDArray from a regular Python list using the 'array' function. 

.. code-block:: python

	import mxnet as mx
	# create a 1-dimensional array with a python list
	a = mx.nd.array([1,2,3])
	# create a 2-dimensional array with a nested python list
	b = mx.nd.array([[1,2,3], [2,3,4]])
	{'a.shape':a.shape, 'b.shape':b.shape}


.. note:: ``mxnet.ndarray`` is similar to ``numpy.ndarray`` in some aspects. But the differences are not negligible. For instance:

   - ``mxnet.ndarray.NDArray.T`` does real data transpose to return new a copied
     array, instead of returning a view of the input array.
   - ``mxnet.ndarray.dot`` performs dot product between the last axis of the
     first input array and the first axis of the second input, while `numpy.dot`
     uses the second last axis of the input array.

   In addition, ``mxnet.ndarray.NDArray`` supports GPU computation and various neural
   network layers.

.. note:: ``ndarray`` provides almost the same routines as ``symbol``. Most
  routines between these two packages share the source code. But ``ndarray``
  differs from ``symbol`` in few aspects:

  - ``ndarray`` adopts imperative programming, namely sentences are executed
    step-by-step so that the results can be obtained immediately whereas
    ``symbol`` adopts declarative programming.

  - Most binary operators in ``ndarray`` such as ``+`` and ``>`` have
    broadcasting enabled by default.

Tutorials
---------

.. container:: cards


   .. card::
      :title: NDArray Guide
      :link: ../../tutorials/packages/ndarray/

      The NDArray guide. Start here!



NDArray API of MXNet
--------------------

.. container:: cards

   .. card::
      :title: NDArray
      :link: ndarray.html

      Imperative tensor operations using the NDArray API.


Sparse NDArray API of MXNet
---------------------------

.. container:: cards

   .. card::
      :title: Sparse routines
      :link: sparse/index.html

      Representing and manipulating sparse arrays.



.. toctree::
   :hidden:
   :maxdepth: 2
   :glob:

   ndarray
   */index