Dear all,

According to CHANGES IN R 3.0.0:
 o diag() as used to generate a diagonal matrix has been re-written
      in C for speed and less memory usage.  It now forces the result
      to be numeric in the case diag(x) since it is said to have 'zero
      off-diagonal entries'.

diag(x) does not work for character vector in R 3.0.0 any more. For example,
v <- c("a", "b")

## R 2.15.3
diag(v)
     [,1] [,2]
[1,] "a"  "0"
[2,] "0"  "b"

## R 3.0.0
diag(v)
     [,1] [,2]
[1,]   NA    0
[2,]    0   NA
Warning message:
In diag(v) : NAs introduced by coercion

Regarding the character matrix, it still works. For example,
m <- matrix(c("a", "b", "c", "d"), nrow=2)
diag(m)
## Both R 2.15.3 and 3.0.0
[1] "a" "d"

n <- matrix(0, ncol=2, nrow=2)
diag(n) <- v
n
## Both R 2.15.3 and 3.0.0
     [,1] [,2]
[1,] "a"  "0"
[2,] "0"  "b"

I understand that the above behavior follows exactly what the manual says.
It appears to me that the version in 2.15.3 is more general as it works for
both numeric and character vectors and matrices, whereas the version in
3.0.0 works for character matrices but not character vectors.

Would it be possible to retain the behaviors of diag() for character
vectors? Thanks.

Mike
-- 
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 Mike W.L. Cheung               Phone: (65) 6516-3702
 Department of Psychology       Fax:   (65) 6773-1843
 National University of Singapore
 http://courses.nus.edu.sg/course/psycwlm/internet/
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