Smooth contour of a map
On 17/05/2011 8:24 AM, Pierre Bruyer wrote:
Thank you for your answer, but the function spline() (and a lot of other function in R) can't take in its parameters the original contour which are define by a vector, i.e. :
If you post some reproducible code to generate the contours, someone will show you how to use splines to interpolate them. Duncan Murdoch
##creation of breaks for colors
i<-1
paliers<- c(-1.0E300)
while(i<=length(level[,1]))
{
paliers<- c(paliers,level[i,1])
i<- i+1
}
paliers<- c(paliers, 1.0E300)
Le 17 mai 2011 ? 13:05, Duncan Murdoch a ?crit :
On 11-05-17 5:58 AM, Pierre Bruyer wrote:
I'm a French developer (so I am sorry if my english is not perfect). I have a problem to smooth the contours of a map. I have a dataset with 3 columns, x, y and z, where x and y are the coordinates of my points and z is evaluate to a qualitative elevation and his representation is a set of colors, which is define by levels. The problem is the curve of my contour is so linear, and I would like a more continuous contour. I use the function fitted.contour to draw my map.
If you use a finer grid of x,y values you'll get shorter segments and they will look smoother. You might be able to use a smooth interpolator (e.g. spline()) rather than linear interpolation, but those occasionally do strange things e.g. x<- c(1:4, 5.9, 6:10) y<- c(1:4, 7, 6:10) plot(spline(x,y, n=200), type="l") points(x,y) where one point is out of line with the others, but the curve overcompensates in order to stay smooth. Duncan Murdoch