You can use the following methods to compare strings in R:
Method 1: Compare Two Strings
#case-sensitive comparison string1 == string2 #case-insensitive comparison tolower(string1) == tolower(string2)
Method 2: Compare Two Vectors of Strings
#case-sensitive comparison identical(vector1, vector2) #case-insensitive comparison identical(tolower(vector1), tolower(vector2))
Method 3: Find Similarities Between Two Vectors of Strings
#find which strings in vector1 are also in vector2
vector1[vector1 %in% vector2]
The following examples show how to use each method in practice.
Example 1: Check if Two Vectors Are Identical
The following code shows how to compare two strings in R to determine if they’re equal:
#define two strings
string1
string2
#case-sensitive comparison
string1 == string2
[1] FALSE
#case-insensitive comparison
tolower(string1) == tolower(string2)
[1] TRUE
The case-sensitive comparison returns a value of FALSE since the two strings are not perfectly identical.
However, the case-insensitive comparison returns a value of TRUE since the two strings contain the same characters in the same order, regardless of case.
Example 2: Compare Two Vectors of Strings
The following code shows how to use the identical() function to determine if two vectors of strings are equal:
#define two vectors of strings
vector1 #case-sensitive comparison
identical(vector1, vector2)
[1] FALSE
#case-insensitive comparison
identical(tolower(vector1), tolower(vector2))
[1] TRUE
The case-sensitive comparison returns a value of FALSE since the two vectors don’t contain the exact same strings in the same case.
However, the case-insensitive comparison returns a value of TRUE since the two vectors contain the same strings, regardless of case.
Example 3: Find Similarities Between Two Vectors of Strings
The following code shows how to use the %in% operator to find which strings in one vector belong to another vector:
#define two vectors of strings
vector1
#find which strings in vector1 are also in vector2
vector1[vector1 %in% vector2]
[1] "hey" "hello"
From the output we can see that the strings “hey” and “hello” exist in both vector1 and vector2.
Related: How to Use %in% Operator in R
Additional Resources
The following tutorials explain how to perform other common operations in R:
How to Compare Two Columns in R
How to Compare Two Vectors in R
How to Find Location of Character in String in R
How to Convert a Vector to String in R