[Rd] 1.4.0: mean/sum of logicals

Torsten Hothorn Torsten.Hothorn@rzmail.uni-erlangen.de
Fri, 5 Oct 2001 13:20:54 +0200 (MEST)

the NEWS file in  1.4.0-devel states: 

o   mean() has `data frame' method applying mean column-by-column.
    When applied to non-numeric data mean() now returns NA rather
    than a confusing error message (for compatibility with S4).

which means: 

R> mean(c(TRUE, FALSE))
[1] NA
Warning message: 
argument is not numeric: returning NA in: mean.default(c(TRUE, FALSE)) 


R> sum(c(TRUE, FALSE))
[1] 1

?sum states: 

     sum(..., na.rm=FALSE)


     ...: numeric vectors.

and clearly

R> is.numeric(c(TRUE, FALSE))

this is confusing, isn't it? I think that `sum' and `mean' should take the
same arguments (and one probably will not allow to sum up logicals) or am
I missing something?


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