[R] Fit a smooth closed shape through 4 points

[Alexander Shenkin]

Hello all,

I have sets of 4 x/y points through which I would like to fit closed, 
smoothed shapes that go through those 4 points exactly.  smooth.spline 
doesn't like my data, since there are only 3 unique x points, and even 
then, i'm not sure smooth.spline likes making closed shapes.

Might anyone else have suggestions for fitting algorithms I could employ?

Thanks,
Allie


shapepoints = structure(c(8.9, 0, -7.7, 0, 0, 2, 0, 3.8), .Dim = c(4L,
2L), .Dimnames = list(NULL, c("x", "y")))

smooth.spline(shapepoints)

# repeat the first point to close the shape
shapepoints = rbind(shapepoints, shapepoints[1,])

smooth.spline(shapepoints)