# numpy.stack

numpy.stack(arrays, axis=0, out=None)

  Join a sequence of arrays along a new axis.

  The `axis` parameter specifies the index of the new axis in the dimensions of the result. For example, if `axis=0` it will be the first dimension and if `axis=-1` it will be the last dimension.

  New in version 1.10.0.

  Parameters
    arrays sequence of array_like

      Each array must have the same shape.

    axis int, optional

      The axis in the result array along which the input arrays are stacked.

    out ndarray, optional

      If provided, the destination to place the result. The shape must be correct, matching that of what stack would have returned if no out argument were specified.

  Returns
    stacked ndarray

      The stacked array has one more dimension than the input arrays.

  See also

  `concatenate`

    Join a sequence of arrays along an existing axis.

  `block`

    Assemble an nd-array from nested lists of blocks.

  `split`

    Split array into a list of multiple sub-arrays of equal size.

  Examples

      >>> arrays = [np.random.randn(3, 4) for _ in range(10)]
      >>> np.stack(arrays, axis=0).shape
      (10, 3, 4)

      >>> np.stack(arrays, axis=1).shape
      (3, 10, 4)

      >>> np.stack(arrays, axis=2).shape
      (3, 4, 10)

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

      >>> np.stack((a, b), axis=-1)
      array([[1, 4],
             [2, 5],
             [3, 6]])

previous

numpy.concatenate

next

numpy.block