| lead-lag {dplyr} | R Documentation |
Find the "next" or "previous" values in a vector. Useful for comparing values ahead of or behind the current values.
lead(x, n = 1L, default = NA, order_by = NULL, ...) lag(x, n = 1L, default = NA, order_by = NULL, ...)
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 |
order_by |
override the default ordering to use another vector |
... |
Needed for compatibility with lag generic. |
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)