Get lagging or leading values

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

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

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

Arguments

x

a vector of values

n

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

default

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

Examples

x <- 1:5

lag(x, 1)
#> [1] NA  1  2  3  4
lead(x, 1)
#> [1]  2  3  4  5 NA

# Also works inside of `mutate()`
df <- tidytable(x = 1:5)

df %>%
  mutate(lag_x = lag(x))
#> # A tidytable: 5 × 2
#>       x lag_x
#>   <int> <int>
#> 1     1    NA
#> 2     2     1
#> 3     3     2
#> 4     4     3
#> 5     5     4