peculiar matrices

As far as I can tell from reading The Fine Documentation
(R Language Definition and Intro to R), matrices are supposed
to be of homogeneous types.  Yet giving matrix() an inhomogeneous
list seems to work, although it produces a peculiar object:

v = list(1:3,4,5,"a")
m = matrix(v,nrow=2)
m

     [,1]      [,2]
[1,] Integer,3 5
[2,] 4         "a"


m[1,]

[[1]]
[1] 1 2 3

[[2]]
[1] 3

 (this is R 2.1.1, running under Linux)

Ben,

If you review the structure of 'm' note:

str(m)

List of 4
 $ : int [1:3] 1 2 3
 $ : num 4
 $ : num 5
 $ : chr "a"
 - attr(*, "dim")= int [1:2] 2 2

that it is actually a list, even though:

class(m)

[1] "matrix"


Also:

mode(m)

[1] "list"

typeof(m)

[1] "list"


If you remove the dim attributes, you get:

dim(m) <- NULL
m

[[1]]
[1] 1 2 3

[[2]]
[1] 4

[[3]]
[1] 5

[[4]]
[1] "a"


So I would argue that it is consistent with the documentation in that,
while the printed output is that of a matrix, it is a list, which of
course can handle heterogeneous data types.

This is Version 2.2.0 Patched (2005-10-20 r35979).

  Should there be a check/error? Or is this just analogous to
the joke about going to the doctor and saying "it hurts when
I do this", and the doctor saying "well then, don't do that"?

Maybe more like:

"Doctor, my eye hurts when I drink my tea." and the doctor says, "Well,
remove the spoon from the cup before you drink."

;-)

Regards,

Marc Schwartz