Table of Contents
R provides a wide range of functions to sort and find unique values from a data set. The most commonly used functions for this purpose are the sort() and unique() functions. The sort() function will sort the values of a vector in ascending or descending order while the unique() function will return the unique values of a vector in the same order as they were originally entered. Both of these functions can be used together to quickly find and sort unique values from a data set.
You can use the following methods to find unique values and then sort them in R:
Method 1: Find Unique Values in Vector & Sort Them
#get unique values sorted in ascending order
sort(unique(data))
Method 2: Find Unique Rows in Data Frame & Sort Them
#remove duplicate rows in data frame
df_new = df[!duplicated(df), ]
#display unique rows sorted by values in specific column
df_new = df_new[order(df_new$my_column), ]
The following examples show how to use each method in practice.
Example 1: Find Unique Values in Vector & Sort Them
Suppose we have the following vector in R:
#create vector of values
data <- c(2, 2, 4, 7, 2, 4, 14, 7, 10, 7)
We can use the following syntax to find the unique values in the vector and sort them:
#get unique values sorted in ascending order
sort(unique(data))
[1] 2 4 7 10 14
Notice that the unique values from the vector are returned in ascending order.
We can also use the argument decreasing=TRUE to sort the unique values in descending order:
#get unique values sorted in descending order
sort(unique(data), decreasing=TRUE)
[1] 14 10 7 4 2 Notice that the unique values from the vector are returned in descending order.
Example 2: Find Unique Values in Data Frame & Sort Them
Suppose we have the following data frame in R:
#create data frame
df <- data.frame(team=c('A', 'B', 'A', 'A', 'A', 'B', 'B', 'B', 'A', 'B'),
points=c(2, 10, 7, 7, 2, 4, 14, 7, 2, 7))
#view data frame
df
team points
1 A 2
2 B 10
3 A 7
4 A 7
5 A 2
6 B 4
7 B 14
8 B 7
9 A 2
10 B 7 We can use the following syntax to find the unique rows in the data frame and sort them based on the values in the team column:
#remove duplicate rows in data frame
df_new = df[!duplicated(df), ]
#sort unique rows based on values in team column
df_new = df_new[order(df_new$team, df_new$points), ]
#view new data frame
df_new
team points
1 A 2
3 A 7
2 B 4
6 B 7
7 B 10
8 B 14 Notice that the unique rows are returned and sorted based on the values in the team column, then by the values in the points column.
Related
The following tutorials explain how to perform other common operations in R: