indices specifying elements to extract or
replace. Indices are
vectors or empty (missing) or
values are coerced to integer as by
as.integer (and hence truncated towards
zero). Character vectors will be matched to the
names of the object (or for
‘Character indices’ below for further details.
... can be logical vectors, indicating
elements/slices to select. Such vectors are recycled if
necessary to match the corresponding extent.
... can also be negative integers,
indicating elements/slices to leave out of the selection.
When indexing arrays by
[ a single argument
i can be a matrix with as many columns as there
are dimensions of
x; the result is then a vector
with elements corresponding to the sets of indices in
each row of
An index value of
NULL is treated as if it were