在R中按组创建连续年份的计数

library(dplyr)
library(tidyr)

df <- data.frame(group = c("A", "A", "A", "B", "B", "B", "B", "C", "C"),
                 year = c(2010, 2011, 2013, 2010, 2011, 2012, 2013, 2011, 2012))

df <- df %>%
  group_by(group) %>%
  mutate(count = row_number() + min(year) - 1)

df <- df %>%
  ungroup()

print(df)

# A tibble: 9 x 3
  group  year count
  <chr> <dbl> <dbl>
1 A      2010  2010
2 A      2011  2011
3 A      2013  2012
4 B      2010  2010
5 B      2011  2011
6 B      2012  2012
7 B      2013  2013
8 C      2011  2011
9 C      2012  2012