On 11/8/2007 11:51 AM, zhijie zhang wrote: > Dear friends, > My dataset is like the following: > x y mcpvalue > 0.4603578 0.6247629 1.001 > 0.4603715 0.6247788 1.001 > 0.4603852 0.6247948 1.001 > 0.4110561 0.5664841 0.995 > The x and y variables are unsorted. > I use the function image(x,y,mcpvalue) to generate a plot, but the error > is that "increasing 'x' and 'y' values are expected". So i use > image(x=seq(min(x),max(x)), y=seq(min(y),max(y)),z=as.matrix > (result$mcpvalue)) > to do it again, but there is still an error "dimensions of z are not > length(x)(-1) times length(y)(-1)". > Anybody can show me how to use the image() correctly with the original x/y > unsorted?
You can't, it doesn't know how to handle that kind of data. image() is designed to display a matrix of values. The x and y values tell it where to put the rows and columns of the matrix. You have a set of points. You need to fit a surface to them, evaluate the surface on a grid, and pass that to image(). There are many ways to do that; the akima package has the interp() function for instance. Duncan Murdoch ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
