[R] image plot with multiple x values

baptiste Auguié ba208 at exeter.ac.uk
Fri Aug 17 20:51:59 CEST 2007


New to R, I don't find a way to plot the following data with image():

x is a N * M matrix
y is a vector of length M
z is a N*M matrix

I wish to plot z as a greyscale image, but my x axis is different for  
every row of the z data.

Here is a minimal example,

> theta<-c(3:6) # N
> y<-c(1:5) # M
> x<-theta%*%t(y)# N * M
> z<-sin(x) # N * M
> image(z)

This doesn't give what I want, as the x axis needs to be shifted as  
we go from line to the following. (probably clearer if you plot  
matplot(x,z): the curves are shifted)

The way I see it, I need either to construct a bigger matrix with all  
possible values of x giving the new dimension and arbitrary values  
for the missing points, or find a plotting function that would plot  
lines by lines. The ordering of the x and z values is giving me a  
headache on the first idea, and I can't find any option / alternative  
to image.

Thanks in advance!


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