With large numbers of points you might want to consider hexagonal binning instead of scatter plots. I don't know of any tools that both do the binning and take groups into account, but you could think it through and work something out.
-- Gregory (Greg) L. Snow Ph.D. Statistical Data Center Intermountain Healthcare greg.s...@imail.org 801.408.8111 > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-bounces@r- > project.org] On Behalf Of Mike Miller > Sent: Monday, January 24, 2011 5:39 PM > To: David Winsemius > Cc: R-Help List > Subject: Re: [R] determining the order in which points are plotted > > 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. > > 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 ______________________________________________ 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.
