On 3/23/2011 10:27 AM, Grossmann Patrick wrote:
Dear R-Project helpdesk member,
I am currently working on some basic correspondence analysis using the R packages
'ca'. As I compute the CA by example<- ca(data), and plotting example via
plot(example), I am trying to figure out, how to get a certain desired plot, so,
however, my question could be of more general nature.
This probably might not be new to you, but the plotting the result of ca will return a
plot, with red points (triangles if I remember correctly) labeled with the column names
of the original table read in, and blue dots for the row names. What I essentially need
to solve is, to make a plot, which differs in the visualization of the rows. The labels
of the rows should not be displayed at all, plus, certain rows must have a different
color of other rows. Of course, I looked up several manuals and threads already, but
unfortunatly I was not able to get very far beyond "plot(example, labels=0)".
So let us say, I have a table, which looks like this
a b c d
a 1 2 3
b 4 5 6
c 7 8 9
d 0 1 2
with a b c d being the header, and the row.names=1, what I practically need is
a plot, that displays the column names attached as labels to the corresponding
dots/triangles (which is the default case), and the dots referring to the rows
without(!) any labels, PLUS the points corresponding to the first two rows
(a=1 2 3, b = 4 5 6) in a different color (really does not matter which) than
the points corresponding to the last two ones (c = 7 8 9, d = 0 1 2).
I deeply hope, that you are able to help me; if I can help you considering the
formulation of my question, please feel free, to contact me.
[First: please use a more specific and informative subject line in posts
to R-help]
The plot function in the ca package is a bit crippled, since you have no
control over the colors/plot symbols for subsets of the row/col points,
so I'm afraid you can't do what you want with the current CRAN version.
I modified ca::plot.ca.r to return the matrix of coordinates actually
plotted, allowing me to use points() and lines() after the call.
I can send that to you if you like.
HTH
--
Michael Friendly Email: friendly AT yorku DOT ca
Professor, Psychology Dept.
York University Voice: 416 736-5115 x66249 Fax: 416 736-5814
4700 Keele Street Web: http://www.datavis.ca
Toronto, ONT M3J 1P3 CANADA
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