Expand the shape of an array.
Insert a new axis that will appear at the axis position in the expanded array shape.
Previous to NumPy 1.13.0, neither
axis < -a.ndim - 1nor
axis > a.ndimraised errors or put the new axis where documented. Those axis values are now deprecated and will raise an AxisError in the future.
- a : array_like
- axis : int
Position in the expanded axes where the new axis is placed.
- res : ndarray
View of a with the number of dimensions increased by one.
- The inverse operation, removing singleton dimensions
- Insert, remove, and combine dimensions, and resize existing ones
>>> x = np.array([1,2]) >>> x.shape (2,)
The following is equivalent to
>>> 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([, ]) >>> y.shape (2, 1)
Note that some examples may use
np.newaxis. These are the same objects:
>>> np.newaxis is None True