删除所有唯一行 [英] Remove all unique rows

问题描述

我试图弄清楚如何从数据框中删除所有唯一行，但如果它有重复，我希望保留它.例如 - 我希望其中的所有列与 col1 相同:

I am trying to figure out how to remove all unique rows, from a data frame, but if it has a duplicate, I want that to stay in. For Example - I want all columns from this with col1 the same:

df<-data.frame(col1=c(rep("a",3),"b","c",rep("d",3)),col2=c("A","B","C",rep("A",3),"B","C"),col3=c(3,3,1,4,4,3,2,1))
df
  col1 col2 col3
1    a    A    3
2    a    B    3
3    a    C    1
4    b    A    4
5    c    A    4
6    d    A    3
7    d    B    2
8    d    C    1

subset(df,duplicated(col1))
  col1 col2 col3
2    a    B    3
3    a    C    1
7    d    B    2
8    d    C    1

但我想要第 1、2、3、6、7、8 行，因为它们都有相同的第 1 列.如何让第 1 行和第 6 行包含在内?或者，相反，如何删除没有重复的行?

But I want to have rows 1,2,3,6,7,8 since they all have the same col 1. How do I get 1 and 6 to be included? Or, conversely, how do I remove rows that do not have a duplicate?

推荐答案

另一种选择:

subset(df,duplicated(col1) | duplicated(col1, fromLast=TRUE))

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