indices specifying elements to extract or replace. Indices are
character vectors or empty (missing) or
NULL. Numeric 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 matrices/arrays, the
see ‘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
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