Background

@staticmethod
def evaluate(argument: "WaveformVariable | np.ndarray") -> float:
    """
    Calculate the background of a waveform or image. Errors if scalar provided.

    Waveform:
    First, applies smoothing by taking weighted nearest and next-nearest
    neighbour contributions to  y values whose difference from their neighbours
    is more than 0.2 times the total range in y.
    The first 25 and last 25 y values in the signal are averaged to give an
    estimate of the background.

    Image:
    The average pixel value in the 10 by 10 region in the top left of the image
    is returned.
    """
    if isinstance(argument, WaveformVariable):
        Builtin.smooth(argument.y)
        if len(argument.y) < 50:
            return np.mean(argument.y)
        else:
            return (np.mean(argument.y[:25]) + np.mean(argument.y[-25:])) / 2
    elif isinstance(argument, np.ndarray):
        return np.mean(argument[:10, :10])
    else:
        # The check will fail and raise a TypeError
        Background.evaluation_type_check(argument)