attr(x, which, exact = FALSE) attr(x, which) <- value
whichbe matched exactly?
NULLto remove the attribute.
NULLif no exact match is found and no or more than one partial match is found.
The extraction function first looks for an exact match to
amongst the attributes of
x, then (unless
exact = TRUE)
a unique partial match.
options(warnPartialMatchAttr = TRUE) causes
partial matches to give warnings.)
The replacement function only uses exact matches.
Note that some attributes (namely
tsp) are treated specially and have restrictions on
the values which can be set. (Note that this is not true of
levels which should be set for factors via the
levels replacement function.)
The extractor function allows (and does not match) empty and missing
which: the replacement function does not.
Both are primitive functions.
# create a 2 by 5 matrix x <- 1:10 attr(x,"dim") <- c(2, 5)
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