使用dplyr的条件累积和

library(dplyr)

# 创建一个示例数据框
df <- data.frame(
  group = c("A", "A", "B", "B", "B", "C"),
  value = c(1, 2, 3, 4, 5, 6)
)

# 使用条件累积和计算每个组内value的累积和
df <- df %>%
  group_by(group) %>%
  mutate(cumulative_sum = cumsum(value))

# 打印结果
print(df)

# A tibble: 6 x 3
# Groups:   group [3]
  group value cumulative_sum
  <chr> <dbl>          <dbl>
1 A         1              1
2 A         2              3
3 B         3              3
4 B         4              7
5 B         5             12
6 C         6              6