numpy.expand_dims¶
-
numpy.
expand_dims
(a, axis)[source]¶ Expand the shape of an array.
Insert a new axis that will appear at the axis position in the expanded array shape.
Note
Previous to NumPy 1.13.0, neither
axis < -a.ndim - 1
noraxis > a.ndim
raised errors or put the new axis where documented. Those axis values are now deprecated and will raise an AxisError in the future.Parameters: a : array_like
Input array.
axis : int
Position in the expanded axes where the new axis is placed.
Returns: res : ndarray
Output array. The number of dimensions is one greater than that of the input array.
See also
Examples
>>> x = np.array([1,2]) >>> x.shape (2,)
The following is equivalent to
x[np.newaxis,:]
orx[np.newaxis]
:>>> y = np.expand_dims(x, axis=0) >>> y array([[1, 2]]) >>> y.shape (1, 2)
>>> y = np.expand_dims(x, axis=1) # Equivalent to x[:,np.newaxis] >>> y array([[1], [2]]) >>> y.shape (2, 1)
Note that some examples may use
None
instead ofnp.newaxis
. These are the same objects:>>> np.newaxis is None True