[R] Contour Plots
Martin Maechler
maechler at stat.math.ethz.ch
Fri Jul 11 10:26:38 CEST 2003
>>>>> "Riley" == Riley Metzger <alpha_white_wolf at hotmail.com>
>>>>> on Thu, 10 Jul 2003 13:53:56 -0400 writes:
Riley> Hello, I'm a grad. student in statistics and am
Riley> looking for some information on how R draws its
Riley> contours. I suspect you are using a Bezier spline.
I don't know if what we do can be called a Bezier spline (it
would be the most simple, i.e. "linear" one...), but in any
case, we simply do linear interpolation :
contour() uses data on a grid.
The only thing you have to do is drawing line segments in
rectangles. In the following case, given the z-values in points
A & B, find the "*" intersection on the AB line
A & C, find the "+" intersection on the AC line
now draw the segment from "*" to "+"
A ____*____ B
| . |
| . |
| . |
|. |
+ |
|_________|
C D
(and all you guys with silly proportional fonts in your e-mail
reader will not see a nice picture above ....)
Regards,
Martin Maechler <maechler at stat.math.ethz.ch> http://stat.ethz.ch/~maechler/
Seminar fuer Statistik, ETH-Zentrum LEO C16 Leonhardstr. 27
ETH (Federal Inst. Technology) 8092 Zurich SWITZERLAND
phone: x-41-1-632-3408 fax: ...-1228 <><
More information about the R-help
mailing list