[R] Bug in coplot()

John Maindonald john.maindonald at anu.edu.au
Fri Jan 15 11:41:05 CET 1999

I am using R0.63.1 under Windows 95.

Settings of <number> and <interval> when coplot is called
are ignored, except for generating a warning.  For example:

> data(quakes)
> coplot(long ~ lat | depth * mag, data = quakes, number=3) 
Warning: parameter "number" couldn't be set in high-level plot() function

The warning is repeated ad nauseum.

The following changes seem needed:
(1) Make <number=6> and <overlap=0.5> named arguments
    to coplot.  (If used as ... parameters, there is an
    attempt to use them as plot parameters, generating the
    warning messages.)

(2) Within the braces following 
    include the statements

      if(length(number)==1) number<-rep(number,2)      # Add 
      if(length(overlap)==1) overlap<-rep(overlap,2)   # Add 

(3) Change the first invocation of <co.intervals> in <coplot>
    from <else a.intervals <- co.intervals(a)> to

    else a.intervals <- co.intervals(a,number=number[1],overlap=overlap[1]) # Replacement

    and the second invocation from
    from <b.intervals <- co.intervals(b)> to

    else b.intervals <- co.intervals(b,number=number[2],overlap=overlap[2]) # Replacement

(4) One might also check that <number> and <overlap> have
    legal values.

Or is there some better way of attending to this?

John Maindonald               email : john.maindonald at anu.edu.au        
Statistical Consulting Unit,  phone : (6249)3998        
c/o CMA, SMS,                 fax   : (6249)5549  
John Dedman Mathematical Sciences Building
Australian National University
Canberra ACT 0200
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