nth

0th

Percentile

Extract the first, last or nth value from a vector.

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.

Usage
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))

Arguments
x
A vector
n
For nth_value, a single integer specifying the position. If a numeric 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 atomic vectors, where a missing value of the appropriate type is return, and for lists, where a NULL is return. For more complicated objects, you'll need to supply this value.
Value

A single value. [[ is used to do the subsetting.

Aliases
  • first
  • last
  • nth
Examples
x <- 1:10
y <- 10:1

last(x)
last(x, y)
Documentation reproduced from package dplyr, version 0.4.0.9000, License: MIT + file LICENSE

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