nth {dplyr} | R Documentation |
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)
last(y)
nth(x, 1)
nth(x, 5)
nth(x, -2)
nth(x, 11)
last(x)
# Second argument provides optional ordering
last(x, y)
# These functions always return a single value
first(integer())