def differentiate_shown_data(neighbors=1, fyname=1, **kwargs):
    """
    Differentiates the data visible on the specified axes using
    fun.derivative_fit() (if neighbors > 0), and derivative() otherwise.
    Modifies the visible data using manipulate_shown_data(**kwargs)
    """

    if neighbors:
        def D(x,y): return _fun.derivative_fit(x,y,neighbors)
    else:
        def D(x,y): return _fun.derivative(x,y)

    if fyname==1: fyname = '$\\partial_{x(\\pm'+str(neighbors)+')}$'

    manipulate_shown_data(D, fxname=None, fyname=fyname, **kwargs)