R help - Jul 2006 - arules package: using image() deliveres unexpected results

Dear Collegues,
 
it seems like there is a problem with the image()-method in the package arules.
 
Using an ordninary matrix works fine:
image(matrix(rnorm(200), 10, 20), axes = FALSE, col=brewer.pal(9,
"Blues") )
delivers an image with blue colors and no axes.
 
Using an object of the class "associations" (arules package) does not
work:
 
image(items(ta.eclat), axes = FALSE, col=brewer.pal(9, "Blues") )
delivers an error message telling that the argument "col" matches to
several formal arguments.
 
image(items(ta.eclat), axes = FALSE)
delivers no error message but draws axes, which clearly should not be the case

In the source code of arules I couldn't find any definition of the
image-function (especially no image.R-file.)

What I want to do is drawing an image of itemsets as produced by eclat, with
blue colors and the item labels at the x-axe.

Does anybody know help?

Thank You, Markus
 
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Markus:
> it seems like there is a problem with the image()-method in the package
> arules.
For problems with packages, please contact the maintainer or at least have
im Cc as the posting guide tells you.
> Using an ordninary matrix works fine:
> image(matrix(rnorm(200), 10, 20), axes = FALSE, col=brewer.pal(9,
"Blues") )
Note that image() is a generic function, the methods called in your
example above is rather different from the methods below.
> delivers an image with blue colors and no axes.
>
> Using an object of the class "associations" (arules package) does
not work:
>
> image(items(ta.eclat), axes = FALSE, col=brewer.pal(9, "Blues") )
> delivers an error message telling that the argument "col" matches
to
> several formal arguments.
So maybe you should check what arguments are allowed for the method in
arules:
  help("image", package = "arules")
tells you to look that essentially levelplot() is called and
  help("levelplot", package = "lattice")
shows that there are two arguments starting with `col' (col.regions and
colorkey) and that there is no argument `axes'.
> In the source code of arules I couldn't find any definition of the
> image-function (especially no image.R-file.)
It's in itemMatrix.R, because it is the image() method for
"itemMatrix"
objects. You can also see in
  getMethod("image", "itemMatrix")
that it calls the "dgTMatrix" method:
  getMethod("image", "dgTMatrix")
which calls levelplot().

A note to Michael (arules maintainer): the link from the image()
documentation in arules to Matrix is broken (should be to
"dgTMatrix-class") and maybe you should also link levelplot() in
lattice
explicitely?

hth,
Z