You can use the unique() function in R to find unique values in a column of a data frame.
This tutorial provides several examples of how to use this function with the following data frame:
#create data frame
df <- data.frame(team=c('A', 'A', 'B', 'B', 'C', 'C'),
points=c(90, 99, 90, 85, 90, 85),
assists=c(33, 33, 31, 39, 34, 34),
rebounds=c(30, 28, 24, 24, 28, 28))
#view data frame
df
team points assists rebounds
1 A 90 33 30
2 A 99 33 28
3 B 90 31 24
4 B 85 39 24
5 C 90 34 28
6 C 85 34 28
Example 1: Find Unique Values in Column
The following code shows how to find unique values in the ‘team’ column:
#find unique values in 'team' column
unique(df$team)
[1] "A" "B" "C"
We can use similar syntax to find unique values in the ‘points’ column:
#find unique values in 'points' column
unique(df$points)
[1] 90 99 85
Example 2: Find & Sort Unique Values in Column
The following code shows how to find and sort unique values in the ‘points’ column:
#find and sort unique values in 'points' column
sort(unique(df$points))
[1] 85 90 99
We can also sort unique values in a descending order:
#find and sort unique values in 'points' column
sort(unique(df$points), decreasing=TRUE)
[1] 99 90 85
Example 3: Find & Count Unique Values in Column
The following code shows how to find and count the number of each unique value in the ‘points’ column:
#find and count unique values in 'points' column
table(df$points)
85 90 99
2 3 1
From the output we can see:
- The value 85 occurs 2 times.
- The value 90 occurs 3 times.
- The value 99 occurs 1 time.
Additional Resources
The following tutorials explain how to perform other common operations in R:
How to Perform a COUNTIF Function in R
How to Find and Count Missing Values in R
How to Count Number of Occurrences in Columns in R
