![[Stable]](figures/lifecycle-stable.svg)
difference(x, lag = 1, differences = 1, default = NA, order_by = NULL)Arguments
- x
Vector of values
- lag
A positive integer indicating which lag to use.
- differences
A positive integer indicating the order of the difference.
- default
Value used for non-existent rows. Defaults to
NA.- order_by
Override the default ordering to use another vector or column
Value
A numeric vector of the same length as x.
See also
Examples
# examples from base
difference(1:10, 2)
#> [1] NA NA 2 2 2 2 2 2 2 2
difference(1:10, 2, 2)
#> [1] NA NA NA NA 0 0 0 0 0 0
x <- cumsum(cumsum(1:10))
difference(x, lag = 2)
#> [1] NA NA 9 16 25 36 49 64 81 100
difference(x, differences = 2)
#> [1] NA NA 3 4 5 6 7 8 9 10
# Use order_by if data not already ordered (example from dplyr)
library(dplyr, warn.conflicts = FALSE)
tsbl <- tsibble(year = 2000:2005, value = (0:5)^2, index = year)
scrambled <- tsbl %>% slice(sample(nrow(tsbl)))
#> Warning: Current temporal ordering may yield unexpected results.
#> ℹ Suggest to sort by ``, `year` first.
wrong <- mutate(scrambled, diff = difference(value))
#> Warning: Current temporal ordering may yield unexpected results.
#> ℹ Suggest to sort by ``, `year` first.
#> Warning: Current temporal ordering may yield unexpected results.
#> ℹ Suggest to sort by ``, `year` first.
arrange(wrong, year)
#> # A tsibble: 6 x 3 [1Y]
#> year value diff
#> <int> <dbl> <dbl>
#> 1 2000 0 -4
#> 2 2001 1 -15
#> 3 2002 4 NA
#> 4 2003 9 -16
#> 5 2004 16 16
#> 6 2005 25 24
right <- mutate(scrambled, diff = difference(value, order_by = year))
#> Warning: Current temporal ordering may yield unexpected results.
#> ℹ Suggest to sort by ``, `year` first.
#> Warning: Current temporal ordering may yield unexpected results.
#> ℹ Suggest to sort by ``, `year` first.
arrange(right, year)
#> # A tsibble: 6 x 3 [1Y]
#> year value diff
#> <int> <dbl> <dbl>
#> 1 2000 0 NA
#> 2 2001 1 1
#> 3 2002 4 3
#> 4 2003 9 5
#> 5 2004 16 7
#> 6 2005 25 9