numpy.expand_dims — NumPy v1.15 Manual (original) (raw)
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. |
Examples
x = np.array([1,2]) x.shape (2,)
The following is equivalent to x[np.newaxis,:] or 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:
np.newaxis is None True