Bug in tapply with factors containing NAs (PR#6672)

Full_Name: George Leigh
Version: 1.8.1
OS: Windows 2000
Submission from: (NULL) (203.25.1.208)


The following example gives the correct answer when the first argument of tapply
is a numeric vector, but an incorrect answer when it is a factor.  If the
function used by tapply is "length", the type and contents of the first argument
should make no difference, provided it has the same length as the second
argument.

x = c(NA, 1)
y = factor(x)
tapply(x, y, length)

1 
1

tapply(y, y, length)

1 
2