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))
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