expand_dims(a, axis)

Insert a new axis that will appear at the :None:None:`axis` position in the expanded array shape.

Parameters

a : array_like

Input array.

axis : int or tuple of ints

Position in the expanded axes where the new axis (or axes) is placed.

deprecated

Passing an axis where axis > a.ndim will be treated as axis == a.ndim , and passing axis < -a.ndim - 1 will be treated as axis == 0 . This behavior is deprecated.

versionchanged

A tuple of axes is now supported. Out of range axes as described above are now forbidden and raise an :None:None:`AxisError`.

Returns

result : ndarray

View of a with the number of dimensions increased.

Expand the shape of an array.

See Also

atleast_1d

atleast_2d

atleast_3d

doc.indexing

reshape

Insert, remove, and combine dimensions, and resize existing ones

squeeze

The inverse operation, removing singleton dimensions

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)

The following is equivalent to x[:, np.newaxis] :

>>> y = np.expand_dims(x, axis=1)
... y
array([[1],
       [2]])

>>> y.shape
(2, 1)

axis may also be a tuple:

>>> y = np.expand_dims(x, axis=(0, 1))
... y
array([[[1, 2]]])

>>> y = np.expand_dims(x, axis=(2, 0))
... y
array([[[1],
        [2]]])

Note that some examples may use None instead of np.newaxis . These are the same objects:

>>> np.newaxis is None
True

See :

Back References

The following pages refer to to this document either explicitly or contain code examples using this.

numpy.squeeze

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GitHub : /numpy/lib/shape_base.py#512
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