mark.py 文件源码

def __diff(x):
    """
    First derivative/diff (while keeping same size as input)

    Args:
        x (array): numpy array of data

    Returns:
        dx (array): numpy array of first derivative of data
                      (same size as x)
    """
    dx = np.diff(x)
    dx = np.concatenate((dx[0], dx))  # output len == input len
    return dx