R 删除重复行 [英] R remove duplicate rows

问题描述

我有一个数据框，我想在其中删除所有重复的行.例如我的数据框看起来像:

I have a dataframe where I would like to remove all rows with duplicates. For instance my dataframe looks like:

> df <- data.frame(A = c("Happy", "Happy", "Sad", "Confused", "Mad", "Mad"), B = c(1, 2, 3, 4, 5, 6))
> df
         A B
1    Happy 1
2    Happy 2
3      Sad 3
4 Confused 4
5      Mad 5
6      Mad 6

我只想要获取 A 中条目唯一的行:

I only want rows where the entries in A are unique to get:

         A B
1      Sad 3
2 Confused 4

推荐答案

可以试试duplicated

df[!(duplicated(df$A)|duplicated(df$A,fromLast=TRUE)),]
#         A B
#3      Sad 3
#4 Confused 4

或

df[df$A %in% with(as.data.frame(table(df$A)), Var1[Freq==1]),]
#       A B
#3      Sad 3
#4 Confused 4

或

df[colSums(sapply(df$A, `==`, df$A))==1,]
#         A B
#3      Sad 3
#4 Confused 4

或

df[colSums(Vectorize(function(x) x==df$A)(df$A))==1,]

或使用data.table(类似于@beginneR 使用ave)

or using data.table (similar to @beginneR's use of ave)

library(data.table)
setDT(df)[,.SD[.N==1], by=A] 
#          A B
#1:      Sad 3
#2: Confused 4

或

 setDT(df)[df[,.I[.N==1], by=A]$V1]
 #          A B
 #1:      Sad 3
 #2: Confused 4

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