Question about usage

[AllenDowney]

Thanks for this package -- I am trying it out as a replacement for LOWESS, and it seems promising.

I've written this function as a wrapper to work with a pandas Series:

    from whittaker_eilers import WhittakerSmoother

    def make_whittaker_eilers(series):
        """Compute a smooth line.

        series: pd.Series

        returns: pd.Series
        """
        y = series.values
        x = series.index.values

        whittaker_smoother = WhittakerSmoother(
            lmbda=1e4, order=3, data_length=len(y), x_input=x
        )

        smooth = whittaker_smoother.smooth(y)

        return pd.Series(smooth, index=x)

One of the datasets I'm working with has unevenly spaced points, so I'm providing the x values as x_input.

But now I would like to evaluate the smooth function at equally spaced points -- I was expecting a parameter like x_output to indicate where the function should be evaluated, but it looks like it doesn't exist.

Is there another way to do this?

[AnBowell]

Hi there, thanks for giving the package a go!

Yes, you can absolutely do this you'll just need to use weights. Start by inserting the x values you want to evaluate at into your x_input, then insert dummy values of 0 into your y series for them, and finally set the weight of each of the dummy measurements to 0 (leaving actual measurements with a weight of 1). When you run the smoothing on y, it will evaluate it at the filled in x_input.

I understand that it can be quite a pain to do this for some datasets! I may in the future introduce some sort of wrapper function to add functionality like you've suggested to match how these packages usually work in SciPy etc.