使用dplyr进行滚动连接

library(dplyr)

# 创建两个示例数据框
df1 <- data.frame(id = c(1, 2, 3),
                  value = c(10, 20, 30),
                  time = as.Date(c("2022-01-01", "2022-02-01", "2022-03-01")))

df2 <- data.frame(id = c(1, 1, 2, 2, 3, 3),
                  time = as.Date(c("2022-01-15", "2022-02-15", "2022-02-15", "2022-03-15", "2022-03-15", "2022-04-15")),
                  comment = c("comment1", "comment2", "comment3", "comment4", "comment5", "comment6"))

# 使用滚动连接将df2连接到df1
result <- left_join(df1, df2, by = "id") %>%
  filter(time.x <= time.y) %>%
  group_by(id, time.x) %>%
  slice_max(order_by = time.y, n = 1) %>%
  ungroup()

# 输出结果
print(result)