How can I use spline() with ggplot?

Question

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!

score 27 · Accepted Answer · answered Dec 22 '10 at 00:58

27

is this what you want?

n <- 10
d <- data.frame(x = 1:n, y = rnorm(n))
ggplot(d,aes(x,y)) + geom_point() + 
  geom_line(data=data.frame(spline(d, n=n*10)))

answered Dec 22 '10 at 00:58

kohske

that is exactly what I was looking for; nice and simple. thanks – David LeBauer Dec 22 '10 at 01:04
1

what if I want to draw two lines, e.g. for the `x1,y1` and `x2,y2` in `d – David LeBauer Dec 22 '10 at 16:37
1

the answer to the above is: `geom_line(aes(d$x1,d$y1), data=data.frame(spline(x1,y1)))`, although I am not sure why... – David LeBauer Dec 22 '10 at 16:40

1 Answers1