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null plotting symbol ?

4 messages · tblackw@umich.edu, Brian Ripley, Peter Dalgaard +1 more

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I am calling  plot()  with argument pch as a vector of numeric 
symbol codes, the same length as x and y.  Is there some code 
which produces no symbol - a blank - so that I can come back 
with a second call to  points()  and fill in these locations 
using a different fill color and a different symbol size ?  

There's always a work-around, but both x and y are generated 
on the fly by calls to  cumsum(),  so it's inconvenient to put 
NAs into either x or y to suppress plotting that way.  Guess 
I should *try* mixing numeric and character symbol codes, 
although the example in  help("points")  explicitly uses a list 
at that point.  

THX  -  tom blackwell  -  u michigan medical school  -  ann arbor  -
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NAs in pch cause the corresponding points to be omitted.
On Mon, 5 May 2003 tblackw at umich.edu wrote:

            

  
    
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tblackw at umich.edu writes:
Doesn't NA work there??

plot(1:10,pch=c(1:4,NA,6:10))

works for me on Linux, but there could be device dependencies.
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The following produced symbols of different shapes, sizes, and colors in 
R 1.6.2:

  plot(1:4, pch=1:4, col=1:4, cex=1:4)

The same command to S-Plus 6.1 generated a plot with one symbol, color 
and size, complaining, "Too many values for parameter" pch, col, and cex.

hth.  spencer graves
Peter Dalgaard BSA wrote: