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
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