def ramp_1(t,old,new,l):
    """
    A function to simulate tardiness in compliance to social measures.

    Interpolates a parameter between the values 'old' and 'new' using a one parameter ramp function.

    Parameters
    ----------
    t : float or int
        time since last checkpoint
    old : np.array
        parameter value before checkpoint
    new : np.array
        parameter value after checkpoint
    l : float
        time to reach full compliance

    Returns
    -------
    out : np.array
        interpolation between old and new parameter value
    """

    # perform interpolation
    if t <= l:
        f = (1/l)*t
    else:
        f = 1.0
    
    return old + f*(new-old)