在data.frame中显示重复记录并省略单个记录

Question

我一直在努力如何在 R 中只选择重复的 data.frame 行。例如，我的 data.frame 是：

age=18:29
height=c(76.1,77,78.1,78.2,78.8,79.7,79.9,81.1,81.2,81.8,82.8,83.5)
Names=c("John","John","John", "Harry", "Paul", "Paul", "Paul", "Khan", "Khan", "Khan", "Sam", "Joe")
village <- data.frame(Names, age, height)

 Names age height
 John  18   76.1
 John  19   77.0
 John  20   78.1
 Harry  21   78.2
 Paul  22   78.8
 Paul  23   79.7
 Paul  24   79.9
 Khan  25   81.1
 Khan  26   81.2
 Khan  27   81.8
 Sam  28   82.8
 Joe  29   83.5

我想看到如下结果：

Names age height
John  18   76.1
John  19   77.0
John  20   78.1
Paul  22   78.8
Paul  23   79.7
Paul  24   79.9
Khan  25   81.1
Khan  26   81.2
Khan  27   81.8

谢谢你的时间...

Answer 1

使用duplicated两次的解决方案：

village[duplicated(village$Names) | duplicated(village$Names, fromLast = TRUE), ]


   Names age height
1   John  18   76.1
2   John  19   77.0
3   John  20   78.1
5   Paul  22   78.8
6   Paul  23   79.7
7   Paul  24   79.9
8   Khan  25   81.1
9   Khan  26   81.2
10  Khan  27   81.8

一种替代解决方案by：

village[unlist(by(seq(nrow(village)), village$Names, 
                  function(x) if(length(x)-1) x)), ]