The duplicated() function in R is used to get duplicate values in vector or data frame.

The following method shows how to use duplicated function in R with syntax.

Method: Use duplicated() Function

dataframe[duplicated(dataframe$column name), ]

The following example shows how to use this method with example.

First create data frame which having duplicate rows in it:

# Define data frame
df <- data.frame(Machine_name=c("A","B","C","D","A","A","G","B"),
                 Temperature=c(12,9,14,13,18,28,22,23),
                 Pressure=c(20,25,27,29,30,32,39,40))

# Print data frame
print(df)

Output:

  Machine_name Temperature Pressure
1            A          12       20
2            B           9       25
3            C          14       27
4            D          13       29
5            A          18       30
6            A          28       32
7            G          22       39
8            B          23       40

The output shows data frame with duplicate rows.

The following examples shows how to use duplicated() function in R.

Get Duplicate Rows Using duplicated() Function in R

Let’s see how we can use duplicated() function on data frame:

# Define data frame
df <- data.frame(Machine_name=c("A","B","C","D","A","A","G","B"),
                 Temperature=c(12,9,14,13,18,28,22,23),
                 Pressure=c(20,25,27,29,30,32,39,40))

# Find duplicate rows
df[duplicated(df$Machine_name), ]

Output:

Machine_name Temperature Pressure
5            A          18       30
6            A          28       32
8            B          23       40

As we can see in output there are 3 duplicate rows in data frame.

Count Duplicate Rows Using sum() Function in R

Here is example to count duplicate rows in data frame:

We can count duplicate rows using sum() function.The syntax for this function is sum(duplicated(dataframe$column)).

# Define data frame
df <- data.frame(Machine_name=c("A","B","C","D","A","A","G","B"),
                 Temperature=c(12,9,14,13,18,28,22,23),
                 Pressure=c(20,25,27,29,30,32,39,40))

# Count duplicate rows
sum(duplicated(df$Machine_name))

Output:

[1] 3

Using duplicate() function you can easily find duplicate rows in dataset also, count them.