[R] How to properly shade the background panels of an xyplot?

Hi: Here is simplified example of what I am having trouble with: I want to set the gray shade of the background of each panel of a xyplot with its mean. My aim is to be able to compare at a glance which panel has the highest mean. But, in order to achieve this I have to normalize the means between

[R] Grouping multiple runs of multiple datasets in lattice's xyplot (with fixed example code)

Hi: ( A bug in my example code was pointed in the post I sent out earlier today, so I am reposting with the fixed example code) I don't know if my explanation below is clear, so afterwards, I wrote a small a self contained annotated example that generates two plots. I execute simulations with dif

[R] Grouping multiple runs of multiple datasets in lattice's xyplot

Hi: I don't know if my explanation below is clear, so afterwards, I wrote a small a self contained annotated example that generates two plots. I execute simulations with different parameters settings that create several datasets, and for each parameter setting (or dataset) I can obtain different r

[R] How to generate a xyplot with multiple panels using an empty data frame ?

Hi: I am coding some interactive interface using an xyplot from lattice. When a user clicks on a panel of the xyplot, a simulation is executed and the resulting data is plotted on the corresponding panel. The problem is that I start with an empty data frame and only fill it as the user request dat

[R] Can I add a point to a pointsGrob from an xyplot without redrawing ?

Hi: I am a newbie using grid and lattice. I want to update a xyplot without redrawing and I was wondering if there is a way of adding a point to a pointsGrob ? For example, take the example from the "R Graphics Book" page 218-219: grid.newpage() angle <- seq(0, 2*pi, length=21)[-21] x <- cos(ang