lag {poorman}

Compute lagged or leading values

Description

Find the "previous" (lag()) or "next" (lead()) values in a vector. Useful for comparing values behind of or ahead of the current values.

Usage

lag(x, n = 1L, default = NA)

lead(x, n = 1L, default = NA)

Arguments

x

A vector of values

n

A positive integer(1), giving the number of positions to lead or lag by.

default

The value used for non-existent rows (default: NA).

Examples

lag(1:5)
lead(1:5)

x <- 1:5
data.frame(behind = lag(x), x, ahead = lead(x))

# If you want to look more rows behind or ahead, use `n`
lag(1:5, n = 1)
lag(1:5, n = 2)

lead(1:5, n = 1)
lead(1:5, n = 2)

# If you want to define a value for non-existing rows, use `default`
lag(1:5)
lag(1:5, default = 0)

lead(1:5)
lead(1:5, default = 6)