I would like to fit my data using spline(y~x) but all of the examples that I can find use a spline with smoothing, e.g. lm(y~ns(x), df=_).

I want to use spline() specifically because I am using this to do the analysis represented by the plot that I am making.

Is there a simple way to use spline() in ggplot?

I have considered the hackish approach of fitting a line using

geom_smooth(aes(x=(spline(y~x)$x, y=spline(y~x)$y))

but I would prefer not to have to resort to this.

Thanks!