我有数据
library(dplyr, warn.conflicts = FALSE)
mtcars %>%
as_tibble() %>%
select(mpg, qsec) %>%
head(5) %>%
mutate(new_col = c(10, rep(NA, times = nrow(.)-1)))
#> # A tibble: 5 × 3
#> mpg qsec new_col
#> <dbl> <dbl> <dbl>
#> 1 21 16.5 10
#> 2 21 17.0 NA
#> 3 22.8 18.6 NA
#> 4 21.4 19.4 NA
#> 5 18.7 17.0 NA
我需要一个new_col
的解,比如mpg + qsec - lag(new_col)
,但需要递归
预期输出:
#> # A tibble: 5 × 3
#> mpg qsec new_col
#> <dbl> <dbl> <dbl>
#> 1 21 16.5 10
#> 2 21 17.0 28
#> 3 22.8 18.6 13.4
#> 4 21.4 19.4 27.4
#> 5 18.7 17.0 8.3