def get_ewma_derivative(data, ewma_window):
    """Compute the ewma and the derivative

    Parameters
    ----------
    data: pandas DataFrame
    ewma_window: width of the window
    in the rolling average

    Return
    ------
    ewma_derivative: pandas DataFrame
    derivative of the ewma of data

    """

    ewma_derivative = data.ewm(ewma_window, min_periods=0).mean().diff()

    return ewma_derivative