Full_Name: Kevin Wright
Version: 1.5.1
OS: Windows 95
Submission from: (NULL) (170.54.59.160)
Originally posted to r-devel, but after thinking about it more decided that this
is a bug. I encountered an unexpected difference in the way that mean and var
work:
> mean(numeric(0))
[1] NaN
> var(numeric(0))
Error in var(numeric(0)) : `x' is empty
Looking into this, I discovered in mean.default that sum(x)/n
evaluates as > sum(numeric(0))/length(numeric(0))
[1] NaN
The function var seems to evaluate this: > .Internal(cov(numeric(0),NULL,"all.obs"))
Error: `x' is empty
One possible fix would be to modify var to check that the length of x is greater
than 0, otherwise return NaN/NA.
Just for your information (not necessarily the desirable answer), in S-Plus
2000:> mean(numeric(0))
NA> var(numeric(0))
NA
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