[R] Plot Coloured Triangle

[Antje]

Thank you very much!
That's exactly what I need as a starting point :-)

Antje


Greg Snow schrieb:
> Here is an example that may get you started:
> 
> point1 <- c(1.1, 1.7, 255)
> point2 <- c(2.2, 1.5, 180)
> point3 <- c(1.8, 2.2, 60)
> 
> mydf <- as.data.frame( rbind(point1, point2, point3) )
> names(mydf) <- c('x1','x2','red')
> 
> fit <- lm(red~x1+x2, data=mydf)
> 
> df2 <- expand.grid( x1=seq(min(mydf$x1), max(mydf$x1), length=250),
>         x2=seq(min(mydf$x2), max(mydf$x2), length=250) )
> 
> df2$red <- predict(fit, df2)
> 
> library(sp)
> tmp <- point.in.polygon( df2$x1, df2$x2, mydf$x1, mydf$x2)
> 
> df2$red[ tmp==0 ] <- NA
> 
> reds <- sort(unique(df2$red))
> cols <- rgb(reds, 0, 0, maxColorValue=255)
> 
> library(lattice)
> levelplot( red~x1+x2, data=df2, col.regions=cols )
> 
> 
> --
> Gregory (Greg) L. Snow Ph.D.
> Statistical Data Center
> Intermountain Healthcare
> greg.snow at imail.org
> (801) 408-8111
> 
> 
> 
>> -----Original Message-----
>> From: r-help-bounces at r-project.org
>> [mailto:r-help-bounces at r-project.org] On Behalf Of Antje
>> Sent: Monday, June 09, 2008 2:57 AM
>> To: r-help at stat.math.ethz.ch
>> Subject: [R] Plot Coloured Triangle
>>
>> Hi there,
>>
>> I'd like to plot a triangle with each point having a certain
>> color defined and fill it with the interpolated values.
>> The following code shall represent somehow, three points with
>> x,y, and the "amount" of red for example...
>>
>> point1 <- c(1.1, 1.7, 255)
>> point2 <- c(2.2, 1.5, 180)
>> point3 <- c(1.8, 2.2, 60)
>>
>> can anybody give me a hint which methods to use to realize it?
>>
>> Antje
>>
>> ______________________________________________
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>> and provide commented, minimal, self-contained, reproducible code.
>>
> 
>