diff

diff(a, n=1, axis=-1, prepend=None, append=None)

Calculate the n-th discrete difference along the given axis.

Parameters:

a : ndarray

Input array

n : int, optional

The number of times values are differenced. If zero, the input is returned as-is.

axis : int, optional

The axis along which the difference is taken, default is the last axis.

prepend, append : ndarray, optional

Not supported yet

Returns:

diff : ndarray

The n-th differences. The shape of the output is the same as a except along axis where the dimension is smaller by n. The type of the output is the same as the type of the difference between any two elements of a. This is the same as the type of a in most cases.

Notes

Optional inputs prepend and append are not supported yet

Examples

>>> x = np.array([1, 2, 4, 7, 0])
>>> np.diff(x)
array([ 1,  2,  3, -7])
>>> np.diff(x, n=2)
array([  1,   1, -10])

>>> x = np.array([[1, 3, 6, 10], [0, 5, 6, 8]])
>>> np.diff(x)
array([[2, 3, 4],
    [5, 1, 2]])
>>> np.diff(x, axis=0)
array([[-1,  2,  0, -2]])