extend

mdtools.numpy_helper_functions.extend(a, length, axis=-1, fill_value=0)[source]

Extend an axis of an array to a given length by padding a given value at the end of the axis.

Parameters:

a (array_like) – The array to extend.
length (int) – The desired length of a.
axis (int, optional) – The axis to extend. Default: last axis
fill_value (scalar, optional) – The fill value to use to extend the given axis of a to the desired length. Note that you might have to change the data type of the input array to fit the type of fill_value before parsing the array to this function.

Returns:

a_new (numpy.ndarray) – A copy of the input array with the given axis padded with fill_value in such a wax that it has the desired length. If the given axis already had the desired length or is even longer, just the input array is returned.

Examples

>>> a = np.arange(3)
>>> mdt.nph.extend(a, 2)
array([0, 1, 2])
>>> mdt.nph.extend(a, 5)
array([0, 1, 2, 0, 0])
>>> mdt.nph.extend(a, 5, fill_value=9)
array([0, 1, 2, 9, 9])

>>> a = np.arange(6).reshape(2, 3)
>>> mdt.nph.extend(a, 5)
array([[0, 1, 2, 0, 0],
       [3, 4, 5, 0, 0]])
>>> mdt.nph.extend(a, 4, axis=0)
array([[0, 1, 2],
       [3, 4, 5],
       [0, 0, 0],
       [0, 0, 0]])

>>> a = np.arange(12).reshape(2, 2, 3)
>>> mdt.nph.extend(a, 5)
array([[[ 0,  1,  2,  0,  0],
        [ 3,  4,  5,  0,  0]],

       [[ 6,  7,  8,  0,  0],
        [ 9, 10, 11,  0,  0]]])
>>> mdt.nph.extend(a, 3, axis=0)
array([[[ 0,  1,  2],
        [ 3,  4,  5]],

       [[ 6,  7,  8],
        [ 9, 10, 11]],

       [[ 0,  0,  0],
        [ 0,  0,  0]]])
>>> mdt.nph.extend(a, 3, axis=1)
array([[[ 0,  1,  2],
        [ 3,  4,  5],
        [ 0,  0,  0]],

       [[ 6,  7,  8],
        [ 9, 10, 11],
        [ 0,  0,  0]]])