lead-lag

0th

Percentile

Lead and lag.

Lead and lag are useful for comparing values offset by a constant (e.g. the previous or next value)

Usage
lead(x, n = 1L, default = NA, order_by = NULL, ...)

lag(x, n = 1L, default = NA, order_by = NULL, ...)

Arguments
x

a vector of values

n

a postive integer of length 1, giving the number of positions to lead or lag by

default

value used for non-existant rows. Defaults to NA.

order_by

override the default ordering to use another vector

...

Needed for compatibility with lag generic.

Aliases
  • lag
  • lead
  • lead-lag
Examples
library(dplyr) lead(1:10, 1) lead(1:10, 2) lag(1:10, 1) lead(1:10, 1) x <- runif(5) cbind(ahead = lead(x), x, behind = lag(x)) # Use order_by if data not already ordered df <- data.frame(year = 2000:2005, value = (0:5) ^ 2) scrambled <- df[sample(nrow(df)), ] wrong <- mutate(scrambled, prev = lag(value)) arrange(wrong, year) right <- mutate(scrambled, prev = lag(value, order_by = year)) arrange(right, year)
Documentation reproduced from package dplyr, version 0.5.0, License: MIT + file LICENSE

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