Unique Function in R

unique function in R –unique(), eliminates duplicate elements/rows from a vector, data frame or array.

Syntax for unique function in R:

unique(x)

if x is a vector or a data frame, returns a similar object but with the duplicate elements eliminated

Example of Unique function in R:

## unique of a vector
x<-c(1:10,5:15)
unique(x)

in the above example duplicate occurrence of 5,6,7,8,9 and 10 are eliminated and made to occur only once, so the output will be

[1]  1   2   3   4   5   6   7   8   9  10  11  12  13  14  15

Unique function for a column in a data frame:

## unique of a column in a data frame
unique(mtcars$gear)

In the above example we used the mtcars data frame and found the unique values of gear column in mtcars data frame. Instead of 32 entries it gives only 3 unique entries in the gear column

output:
[1]  4   3   5

 

Unique function for a data frame in R: 

Unique function in R can also be applicable for data frame, matrices, and arrays. Let’s see an example on how to use unique function to identify unique elements in a data frame in R

Example:
# simple Data frame creation
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)
df

so the resultant data frame will be

    a    b

1   A    1

2   A    1

3   A    2

4   B   4

5   B   1

6   B   1

7   C   2

8   C   2

  When we apply unique function to the above data frame

## Apply unique function for data frame in R
unique(df)

Duplicate entries in the data frame are eliminated and the final output will be

     a    b
1   A   1
3   A   2
4   B   4
5   B   1
7   C   2

 

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