I wonder about the last sentence in the Details section of the
documentation of 'weighted.mean':
"However, zero weights _are_ handled specially and the corresponding ‘x’
values are omitted from the sum."
The return value of weighted.mean.default is
sum((x * w)[w != 0])/sum(w)
and indeed, it looks as if zero weights are getting special treatment,
but what is wrong with the alternative (equivalent?) expression
sum(x * w) / sum(w)?
Is it a good idea to remove zeros from a vector before applying 'sum' to
it? I don't think so. Anyway, the sentence in the documentation seems to
be uncalled for.
G,
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