[Rd] R 2.5.1 - ?factor examples, details
pinard at iro.umontreal.ca
Tue Jul 3 04:18:06 CEST 2007
Hi, R people.
In ?factor, in the "Examples:" section, we see:
## suppose you want "NA" as a level, and to allowing missing values.
(x <- factor(c(1, 2, "NA"), exclude = ""))
is.na(x) <- TRUE
x #  1 <NA> NA, <NA> used because NA is a level.
#  FALSE TRUE FALSE
I'm a bit confused by this example, as I do not understand the point
being made. Using 'exclude = ""' or not does not change the outcome.
What is being demonstrated by this clause, here? Isn't "NA" a mere
string, not really related to a missing value?
It might also be some kind of linguistic problem, and I'm not a native
English speaker. The "and to allowing" construct sounds strange to me.
I would expect either "and to allow" or "and allowing", but maybe I'm
plainly missing the meaning of the statement.
Could this be clarified somehow?
François Pinard http://pinard.progiciels-bpi.ca
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