# Removing duplicated rows data frame in R [closed]

How can I remove duplicate rows from this example data frame?

A   1
A   1
A   2
B   4
B   1
B   1
C   2
C   2


I would like to remove the duplicates based on both the columns:

A   1
A   2
B   4
B   1
C   2


Order is not important.

## closed as off topic by Andy W, gung♦, whuber♦Feb 14 '13 at 16:37

Questions on Cross Validated are expected to relate to statistics within the scope defined by the community. Consider editing the question or leaving comments for improvement if you believe the question can be reworded to fit within the scope. Read more about reopening questions here. If this question can be reworded to fit the rules in the help center, please edit the question.

## locked by Tim♦Aug 30 '17 at 8:45

This question exists because it has historical significance, but it is not considered a good, on-topic question for this site, so please do not use it as evidence that you can ask similar questions here. This question and its answers are frozen and cannot be changed. More info: help center.

• @whuber shouldn't that be moved to SO? – llrs Mar 31 '17 at 9:55
• @Llopis Yes, but it's too late to do that now--and it was too late when we originally closed it. This kind of question was considered (borderline) on-topic many years ago but nowadays it would be migrated quickly. – whuber Mar 31 '17 at 14:12

unique() indeed answers your question, but another related and interesting function to achieve the same end is duplicated().

It gives you the possibility to look up which rows are duplicated.

a <- c(rep("A", 3), rep("B", 3), rep("C",2))
b <- c(1,1,2,4,1,1,2,2)
df <-data.frame(a,b)

duplicated(df)
[1] FALSE  TRUE FALSE FALSE FALSE  TRUE FALSE  TRUE

> df[duplicated(df), ]
a b
2 A 1
6 B 1
8 C 2

> df[!duplicated(df), ]
a b
1 A 1
3 A 2
4 B 4
5 B 1
7 C 2

• Thanks for mentioning the 'duplicated' function. It can be used to delete duplicated rows based on a subset of the columns. – Joko Jan 20 '16 at 15:27

You are looking for unique().

a <- c(rep("A", 3), rep("B", 3), rep("C",2))
b <- c(1,1,2,4,1,1,2,2)
df <-data.frame(a,b)
unique(df)

> unique(df)
a b
1 A 1
3 A 2
4 B 4
5 B 1
7 C 2

• Thanks Bernd. I thought unique can be applied only for a specific column. I didn't know that it can be used for the entire data frame as well. thanks again – Jana Jan 31 '11 at 20:25