如何使用Dplyr的Summarize以及which（）查找最小值/最大值

dreww2 发表于 Dev

dreww2

我有以下数据：

Name <- c("Sam", "Sarah", "Jim", "Fred", "James", "Sally", "Andrew", "John", "Mairin", "Kate", "Sasha", "Ray", "Ed")
Age <- c(22,12,31,35,58,82,17,34,12,24,44,67,43)
Group <- c("A", "B", "B", "B", "B", "C", "C", "D", "D", "D", "D", "D", "D") 
data <- data.frame(Name, Age, Group)

我想用dplyr

（1）按“组”对数据进行分组（2）显示每个组中的最小和最大年龄（3）显示具有最小和最大年龄的人的姓名

以下代码执行此操作：

data %>% group_by(Group) %>%
     summarize(minAge = min(Age), minAgeName = Name[which(Age == min(Age))], 
               maxAge = max(Age), maxAgeName = Name[which(Age == max(Age))])

哪个效果很好：

  Group minAge minAgeName maxAge maxAgeName
1     A     22        Sam     22        Sam
2     B     12      Sarah     58      James
3     C     17     Andrew     82      Sally
4     D     12     Mairin     67        Ray

但是，如果有多个最小值或最大值，我就会遇到问题：

Name <- c("Sam", "Sarah", "Jim", "Fred", "James", "Sally", "Andrew", "John", "Mairin", "Kate", "Sasha", "Ray", "Ed")
Age <- c(22,31,31,35,58,82,17,34,12,24,44,67,43)
Group <- c("A", "B", "B", "B", "B", "C", "C", "D", "D", "D", "D", "D", "D") 
data <- data.frame(Name, Age, Group)

> data %>% group_by(Group) %>%
+   summarize(minAge = min(Age), minAgeName = Name[which(Age == min(Age))], 
+             maxAge = max(Age), maxAgeName = Name[which(Age == max(Age))])
Error: expecting a single value

我正在寻找两种解决方案：

（1）显示哪个最小或最大名称无关紧要，仅显示一个（即找到的第一个值）（2）如果存在“联系”，则显示所有最小值和最大值

如果不清楚，请让我知道，谢谢！

阴影

您可以使用which.min和which.max获取第一个值。

data %>% group_by(Group) %>%
  summarize(minAge = min(Age), minAgeName = Name[which.min(Age)], 
            maxAge = max(Age), maxAgeName = Name[which.max(Age)])

要获取所有值，请使用例如粘贴适当的collapse参数。

data %>% group_by(Group) %>%
  summarize(minAge = min(Age), minAgeName = paste(Name[which(Age == min(Age))], collapse = ", "), 
            maxAge = max(Age), maxAgeName = paste(Name[which(Age == max(Age))], collapse = ", "))

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