attr(x, which, exact = FALSE)
attr(x, which) <- valuewhich be matched exactly?NULL
to remove the attribute.NULL
if no exact match is found and no or more than one partial match is found.which
amongst the attributes of x, then (unless exact = TRUE)
a unique partial match.
(Setting options(warnPartialMatchAttr = TRUE) causes
partial matches to give warnings.) The replacement function only uses exact matches. Note that some attributes (namely class,
comment, dim, dimnames,
names, row.names and
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
values of which: the replacement function does not. NULL objects cannot have attributes and attempting to
assign one by attr gives an error. Both are primitive functions.attributes# create a 2 by 5 matrix
x <- 1:10
attr(x,"dim") <- c(2, 5)
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