color query in mosaic in package vcd

require(vcd)
mosaic(matrix(1:6, 2, 3), gp=gpar(fill=c("red","gray","blue")), main="three
colors in each row")
mosaic(matrix(1:3, 1, 3), gp=gpar(fill=c("red","gray","blue")), main="only
one color in each row")
I anticipated three colors in the second plot.  My guess is that there 
is a matrix subscript without drop=FALSE somewhere on the inside of one 
of the functions.

This is with
Package: vcd
Version: 1.2-13
Date: 2012-02-19

on
version.string R Under development (unstable) (2013-02-02 r61822)
platform       i386-w64-mingw32
arch           i386
os             mingw32
system         i386, mingw32

	[[alternative HTML version deleted]]

On Fri, 8 Feb 2013, Richard M. Heiberger wrote:

require(vcd)
mosaic(matrix(1:6, 2, 3), gp=gpar(fill=c("red","gray","blue")),
main="three
colors in each row")
mosaic(matrix(1:3, 1, 3), gp=gpar(fill=c("red","gray","blue")),
main="only
one color in each row")
I anticipated three colors in the second plot.  My guess is that there
is a matrix subscript without drop=FALSE somewhere on the inside of
one of the functions.

No, it's more subtle.

If the dimension of the data (1, 3) is not the same as that of the fill
(NULL), they are recycled along the last dimension (see Section 3 of
vignette("strucplot", package = "vcd")). Thus supplying a suitable fill
matrix works:

mosaic(matrix(1:3, 1, 3),
   gp = gpar(fill=matrix(c("red","gray","blue"), 1, 3)))

David: The reason why Rich's original code does not work properly is
that the recycling is not triggered properly. In line 160 of strucplot.R
we check if(length(par) < size) which is not the case here and hence the
dimension is not added. I think we could do

if (length(par) < size | is.null(dim(par)))
   aperm(array(par, dim = rev(d))) else par

That fixes the problem.

Best,
Z

This is with
Package: vcd
Version: 1.2-13
Date: 2012-02-19

on
version.string R Under development (unstable) (2013-02-02 r61822)
platform       i386-w64-mingw32
arch           i386
os             mingw32
system         i386, mingw32

    [[alternative HTML version deleted]]