R语言按年月、国家分组计算字段最大最小值实现方法

现有如下结构的R数据框，需要按国家、年份、月份维度分组，分别计算每组Amount字段的最大值和最小值，输出包含Country/Year/Month/Max/Min五列的汇总表。
测试数据构造代码：

Date <- c("2004-01-01","2004-01-01", "2004-01-15","2004-01-26","2004-02-01","2004-02-03","2004-02-03","2004-02-03","2004-03-01","2004-03-02","2004-03-02","2004-03-06","2004-03-06","2004-03-10", "2004-03-11","2004-03-11","2004-03-12","2004-03-12", "2004-01-01","2004-01-01", "2004-01-15","2004-01-26","2004-02-01","2004-02-03","2004-02-03","2004-02-03","2004-03-01","2004-03-02","2004-03-02","2004-03-06","2004-03-06","2004-03-10",
"2004-03-11","2004-03-11","2004-03-12","2004-03-12", "2004-01-01","2004-01-01", "2004-01-15","2004-01-26","2004-02-01","2004-02-03","2004-02-03","2004-02-03","2004-03-01","2004-03-02","2004-03-02","2004-03-06","2004-03-06","2004-03-10","2004-03-11","2004-03-11","2004-03-12","2004-03-12")
Country <- c("Netherlands", "Netherlands", "Netherlands", "Netherlands", "Netherlands", "Netherlands", "Netherlands", "Netherlands", "Netherlands", "Netherlands", "Netherlands", "Netherlands", "Netherlands", "Netherlands", "Netherlands", "Netherlands", "Netherlands", "Netherlands","Belgium", "Belgium", "Belgium", "Belgium", "Belgium", "Belgium", 
"Belgium", "Belgium", "Belgium", "Belgium", "Belgium", "Belgium", "Belgium", "Belgium", "Belgium", "Belgium", "Belgium", "Belgium", "France", "France", "France","France", "France", "France","France", "France", "France","France", "France", "France","France", "France", "France","France", "France", "France")
Year <- c(2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004, 2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004,2004)
Month <- c(1,1,1,1,2,2,2,2,3,3,3,3,3,3,3,3,3,3,1,1,1,1,2,2,2,2,3,3,3,3,3,3,3,3,3,3,1, 1,1,1,2,2,2,2,3,3,3,3,3,3,3,3,3,3)
Amount <- as.numeric(c(100,50,40,3.50,14.60,11.60,140.20,140.30,147.30,151.20,159.60, 165.60,173.20,177.30,185.30,199.30,217.10,234.90,10.20,3.10,16.00,4.90,17.60,5.30,10.90,12.80,8.40,140.20,140.30,147.30,151.20,159.60,165.60,173.20,177,40,50,.30,185.30,199.30,217.10,234.9,500,300,0,8.40,140.20,140.30,3,147.30,151.20,8,40,30))
df <- data.frame(as.Date(Date),Country,Year, Month, Amount)

之前使用如下代码测试，始终返回全数据集的最大最小值，无法得到分组统计结果：

df %>%
  group_by(Country,Month) %>%
  summarise(MaxAmount = max(Amount, na.rm = T), MinAmount = min(Amount, na.rm = T))

分组统计失效主要有两个原因：

1. 函数命名冲突：如果同时加载了plyr和dplyr包，且没有按顺序加载，会导致group_by、summarise函数调用错误，分组逻辑不生效
2. 分组字段不全：代码中只按Country和Month分组，漏了Year字段，跨年数据会出现统计错误；另外给出的期望示例表存在两处错误：一是所有年份误写为2014，实际数据均为2004年；二是Netherlands2月、3月的最大最小值写反了。

通过显式指定dplyr包前缀调用函数，彻底避免命名冲突，同时补全分组字段：

library(dplyr)

result <- df %>%
  dplyr::group_by(Country, Year, Month) %>%
  dplyr::summarise(
    Max = max(Amount, na.rm = TRUE),
    Min = min(Amount, na.rm = TRUE),
    .groups = "drop" # 统计完成后自动取消分组，不影响后续数据操作
  )

运行后得到的正确统计结果如下：

小提示：如果需要同时使用plyr和dplyr，一定要先加载plyr再加载dplyr，否则就全程用dplyr::前缀调用函数，就不会出现分组失效的问题。

内容的提问来源于stack exchange，提问作者Zuzana