Home: 2. Variable Types

In this lesson we will introduce different types of variables, including character, numeric, integer, logical.

Types of Variables

Character

A character is a type of class that contains a string of characters. For example, a name is a string of characters (or letters).
In the example below, I’ve saved my name “Jenny” to a variable I’ve called “my_char”.

my_char <- "Jenny"

To check what type of variable you have, you can use the class() function
All we have to do is insert our variable (my_char) within the parentheses of our function

Note, we will review functions in a following lesson, but for now just run the below line of code and see what gets returned

class(my_char)

[1] "character"

As you can see, R returned the word “character” as we may have expected
We can also use the is.character() function to check if our variable is a character. This function will return either TRUE or FALSE

is.character(my_char)

[1] TRUE

Numeric

Numeric is a type of class that contains whole numbers or numbers with decimals
Let’s test out a couple of examples
We will first assign a number to a new variable (my_num1 or my_num2)
And then we’ll ask R to print (or return) the value for us

my_num1 <- 22 # my favorite number!
my_num1

[1] 22

my_num2 <- 22.22
my_num2

[1] 22.22

Let’s check the classes of the variables we’ve just created

class(my_num1)

[1] "numeric"

class(my_num2)

[1] "numeric"

We can see that both of our variables are numeric

Integer

An integer is a type of class that contains only whole numbers
Of course, this is similar to the numeric class, but without decimals. So how does R know if a whole number is numeric or an integer?
By default, R will assign any whole number to the numeric class. We observed this above when we saw the class of the number 22 was numeric
However, as we’ll see below, you can convert a numeric class to an integer using the as.integer() function

my_int1 <- as.integer(22)
class(my_int1)

[1] "integer"

But, what happens if we try to convert a number with a decimal to an integer?

my_int2 <- as.integer(22.22)
class(my_int2)

[1] "integer"

This works! It has successfully converted 22.22 to an integer
However, it is important to note that 22.22 was forced to become a whole number
So, if we look at my_int2, it is now the whole number 22 rather than the decimal 22.22

my_int2

[1] 22

Logical

Logical is a special type of class that contains only two possible values: TRUE or FALSE
Please note that the logical values must be written in all caps with no quotes

log1 <- TRUE
log2 <- FALSE

Once again, we’ll check the classes of the variables we’ve just created

class(log1)

[1] "logical"

class(log2)

[1] "logical"

What happens if we try the following?

log3 <- "TRUE"
class(log3)

[1] "character"

Because TRUE is in “” here, by default R assigns this to the character class

log4 <- true

This example doesn’t even run! R gives us an error here saying “object ‘true’ not found”

Summary

In this lesson, we learned about different types of variables. We specifically focused on 4 of the most common variables:

Character: list of character strings
Numeric: whole numbers OR numbers with decimals
Integer: Only whole numbers
Logical: TRUE or FALSE

Exercises

In this exercise, we’ll return to our three fabulous female artists: Jennifer Lopez, Taylor Swift, and Miley Cyrus. In the exercises in lesson we, we compared their heights, which we can see below.

Remember to run the code before moving on.

jennifer <- 64.57
taylor <- 70.87
miley <- 64.96

What kind of variables are we dealing with here? Are they characters, numeric, integers, or logical? Once you think you know the answer, in the R Chunk below, use the class() function to see if you’re right. Test it out with any or all of the artists.

Now, convert Jennifer’s height to an integer. What number number is returned?

Save your results to a new variable jennifer_int. Do the same steps for Miley and save the result to miley_int.

When we’re dealing with integers, are Miley and Jennifer the same height?

Create three new variables with each woman’s respective full names (first and last). Save your three variables asjennifer_name, taylor_name, and miley_name.

Hint: ff you get an error that says “object not found”, return to the very first R Chunk in this lesson and see how I saved my name.

What type of variables are these? Test it out with any or all of the artists.

2. Variable Types