Data types in R

In R it is important to understand that there are different types of data, as many functions and operations only work with specific data types, e.g. arithmetic operations only work with numbers, but not with text.

There are six different data types in R:

• Numeric - decimal numbers, such as 3.14. They can be negative.
• Integer - whole numbers, such as 4. They can also be negative. This data type can also count as numeric.
• Logical - boolean data: FALSE or TRUE
• Character - symbols, letters, words or phrases. The data is denoted using quotation marks: "This is text."
• Complex - data that contains complex number, such as 9 + 3i.
• Raw - holds raw bytes. This is a rather unusual data type and only mentioned for the sake of completeness.

Checking the Type of Data in R

You can find out the type (or class) of any object using the class() function:

#create variables with different data types
test_scores <- 87.9
final_grade <- "B"
pass_logical <- TRUE

#check the data type using the class() function

class(test_scores)
Output: [1] "numeric"

class(final_grade)
Output: [1] "character"

class(pass_logical)
Output: [1] "logical"

Another way to check what type of data you have is by using the logical function is.[classOfData](). R will return with either TRUE or FALSE:

is.numeric(test_scores)
Output: [1] "TRUE"

is.logical(final_grade)
Output: [1] "FALSE"

Coercing Data:

You can also change the type/class of a variable by using the as.[classOfData]() function. This will convert whatever data type you have stored in a variable to a different, specified data type.

#create a variable and assign a 'numeric'. 
test_scores <- 87.9
#check the data type
class(test_scores)
Output: [1] "numeric"
#convert this data type into 'character'
test_scores_char <- as.character(test_scores)
test_scores_char #print out the value of the new variable
Output: [1] "87.9"
#the converted data is stored in a new variable called test_score_char. Check the class:
class(test_scores)
Output: [1] "character"

You need to be careful with this function, as you cannot convert all data types into one another. For instance, you will receive an error message, when you try to convert a character string into a numeric:

#create a variable and assign a 'character'. 
final_grade <- "B"
#check the data type
class(final_grade)
Output: [1] "character"
#convert this data type into a 'numeric'
final_grade_numeric <- as.numeric(final_grade)
Output: "NA
Warning message: NAs introduced by coercion"

The is.[classOfData]() and the as.[classOfData]() function look slightly different depending on the data type:

Data type	is.[classOfData]() function	as.[classOfData]() function
Character	is.character()	as.character()
Complex	is.complex()	as.complex()
Logical	is.logical()	as.logical()
Numeric	is.numeric()	as.numeric()
Integers	is.integer()	as.integer()