On 22/06/2010 9:29 AM, dbeest wrote:
Hi All,
I'm having difficulty making a contour plot a would like some help.
A standard contourplot can be made by having an x,y, and some matrix (shape
x*y) with contents:
x = 1:10
y = 1:10
cont <- matrix(runif(100,min=1,max=2),nrow=10,ncol=10)
filled.contour(x,y,cont)
Looks very nice.
Sometimes data comes in a different format however. Basically an x and an y,
and a vector z with all realisations of some f(x,y). The only R way of
making a contour plot out of this I can find is:
You should interpolate the data to a grid, and use the first method.
The interp function in the akima package can do this. For example,
library(lattice)
x = runif(100,min=0,max=10)
y = runif(100,min=0,max=10)
z = runif(100,min=0,max=2)
contourplot(z ~ x * y, region = TRUE)
library(akima)
grid <- interp(x,y,z)
filled.contour(grid)
Duncan Murdoch
which is pretty ugly. And I don't think it needs to be. Does anyone know a
way to make plots of the first type with data of the second type?
Increasing the number of points to see if that fits better:
x = runif(1000,min=0,max=10)
y = runif(1000,min=0,max=10)
z = runif(1000,min=0,max=2)
contourplot(z ~ x * y, region = TRUE)
...hang on that doesn't plot anything: not my main question, but if anyone
cares to explain why that is..
cheers,
Dennis
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