How to fit a smooth curve to my data in R?
I'm trying to draw a smooth curve in R. I have the following simple toy data:
> x
[1] 1 2 3 4 5 6 7 8 9 10
> y
[1] 2 4 6 8 7 12 14 16 18 20
Now when I plot it with a standard command it looks bumpy and edgy, of course:
> plot(x,y, type='l', lwd=2, col='red')
How can I make the curve smooth so that the 3 edges are rounded using estimated values? I know there are many methods to fit a smooth curve but I'm not sure which one would be most appropriate for this type of curve and how you would write it in R.
Answer
I like loess() a lot for smoothing:
x <- 1:10
y <- c(2,4,6,8,7,12,14,16,18,20)
lo <- loess(y~x)
plot(x,y)
lines(predict(lo), col='red', lwd=2)
Venables and Ripley's MASS book has an entire section on smoothing that also covers splines and polynomials -- but loess() is just about everybody's favourite.