[R] Using image/contour with unevenly spaced data...
David Winsemius
dwinsemius at comcast.net
Fri Nov 19 05:42:02 CET 2010
On Nov 18, 2010, at 10:52 PM, Jason Rupert wrote:
> Is it possible to plot unevenly spaced data with image/contour
> function?
>
> Below is an example of the type uneven data that I'm trying to plot
> with
> image/contour functions. For example, I would like to have the x-
> distance on
> the x-axis and y-distance on the y-axis and then the temperature
> values
> determine the color used. Unfortunately this data was sampled such
> that it is
> not evenly spaced on a Cartesian plot.
>
> I was hoping that image(temp_samples) or contour(temp_samples) or
> something
> similar would work, but my attempts didn't succeed.
>
> Thanks for any feedback insights and hints...
>
> hyp_distance<-seq(1,15)
> angle_deg_val<-seq(0,15)
>
>
> x_distance_val<-NULL
> y_distance_val<-NULL
>
> for(ii in 1:length(hyp_distance))
> {
> for(jj in 1:length(angle_deg_val))
> {
> x_distance_tmp<-
> hyp_distance[ii]*cos(angle_deg_val[jj]*pi/180)
> y_distance_tmp<-
> hyp_distance[ii]*sin(angle_deg_val[jj]*pi/180)
>
> x_distance_val<-c(x_distance_val, x_distance_tmp)
> y_distance_val<-c(y_distance_val, y_distance_tmp)
> }
> }
>
> temperature_vals<-rnorm(length(x_distance_val), 75, 2.2)
>
> temp_samples<-cbind(x_distance_val, y_distance_val, temperature_vals)
library(akima)
ak.fan <- interp(temp_samples[,1],temp_samples[,2],temp_samples[,3] )
contour(ak.fan)
--
David Winsemius, MD
West Hartford, CT
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