These are straightforward wrappers around [[
. The main
advantage is that you can provide an optional secondary vector that defines
the ordering, and provide a default value to use when the input is shorter
than expected.
nth(x, n, order_by = NULL, default = default_missing(x)) first(x, order_by = NULL, default = default_missing(x)) last(x, order_by = NULL, default = default_missing(x))
x | A vector |
---|---|
n | For If a double is supplied, it will be silently truncated. |
order_by | An optional vector used to determine the order |
default | A default value to use if the position does not exist in
the input. This is guessed by default for base vectors, where a
missing value of the appropriate type is returned, and for lists, where
a For more complicated objects, you'll need to supply this value.
Make sure it is the same type as |
A single value. [[
is used to do the subsetting.
x <- 1:10 y <- 10:1 first(x)#> [1] 1last(y)#> [1] 1nth(x, 1)#> [1] 1nth(x, 5)#> [1] 5nth(x, -2)#> [1] 9nth(x, 11)#> [1] NAlast(x)#> [1] 10# Second argument provides optional ordering last(x, y)#> [1] 1#> [1] NA