determining the order in which points are plotted
On 2011-01-24 16:39, Mike Miller wrote:
On Mon, 24 Jan 2011, David Winsemius wrote:
On Jan 24, 2011, at 6:49 PM, Mike Miller wrote:
I make plenty of scatterplots, especially using scatterplot.matrix from library(car). One thing I don't know how to do is determine which points are plotted last. Sometimes I plot a large number of points for multiple groups represented by different colors.
?points
Thanks for the tip. I guess I would make vectors for x, y and col in the
desired order and the first elements would be plotted first:
Graphical parameters ?pch?, ?col?, ?bg?, ?cex? and ?lwd? can be
vectors (which will be recycled as needed) giving a value for each
point plotted. If lines are to be plotted (e.g. for ?type = "b"?/
the first element of ?lwd? is used.
Suppose I'm plotting 10,000 points in a 10 x 10 scatterplot matrix
(roughly what I'm actually doing). That's a total of 1 million points.
It might take a while, but I can wait. However, I'm not sure how to get
the coordinates right for additional points in a scatterplot matrix.
Maybe I need to study that source code.
10 x 10 strikes me as pretty near the limit of usefulness of a pairs plot. You might want to investigate the xysplom() function in pkg:HH. You'll have to write your own panel function, possibly subsetting your data with the scale() function. Peter Ehlers
I did figure out recently how to use transparent points to get the axes right. Color "#ffffff00" does that trick for me -- that's white color with zero opaqueness, full transparency. Mike -- Michael B. Miller, Ph.D. Minnesota Center for Twin and Family Research Department of Psychology University of Minnesota