numpy.ma.expand_dims()

Expand the shape of an array.

Expands the shape of the array by including a new axis before the one specified by the axis parameter. This function behaves the same as numpy.expand_dims but preserves masked elements.

Examples

>>> import numpy.ma as ma
>>> x = ma.array([1, 2, 4])
>>> x[1] = ma.masked
>>> x
masked_array(data = [1 -- 4],
             mask = [False  True False],
       fill_value = 999999)
>>> np.expand_dims(x, axis=0)
array([[1, 2, 4]])
>>> ma.expand_dims(x, axis=0)
masked_array(data =
 [[1 -- 4]],
             mask =
 [[False  True False]],
       fill_value = 999999)

The same result can be achieved using slicing syntax with np.newaxis.

>>> x[np.newaxis, :]
masked_array(data =
 [[1 -- 4]],
             mask =
 [[False  True False]],
       fill_value = 999999)