numpy.ma.
expand_dims
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 nor axis > 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.
axis < -a.ndim - 1
axis > a.ndim
Input array.
Position in the expanded axes where the new axis is placed.
View of a with the number of dimensions increased by one.
See also
squeeze
The inverse operation, removing singleton dimensions
reshape
Insert, remove, and combine dimensions, and resize existing ones
doc.indexing, atleast_1d, atleast_2d, atleast_3d
doc.indexing
atleast_1d
atleast_2d
atleast_3d
Examples
>>> x = np.array([1,2]) >>> x.shape (2,)
The following is equivalent to x[np.newaxis,:] or x[np.newaxis]:
x[np.newaxis,:]
x[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 of np.newaxis. These are the same objects:
None
np.newaxis
>>> np.newaxis is None True