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Data Types in R

2017/02/17

Introduction

In the previous post, we learnt how to create variables in R. In this post, we will learn about the following data types:

  • numeric/double
  • integer
  • character
  • logical
  • date/time

Numeric

In R, numbers are represented by the data type numeric. We will first create a variable and assign it a value. Next we will learn a few methods of checking the type of the variable.

# create two variables
number1 <- 3.5
number2 <- 3

# check data type
class(number1)
## [1] "numeric"
class(number2)
## [1] "numeric"
# check if data type is numeric
is.numeric(number1)
## [1] TRUE
is.numeric(number2)
## [1] TRUE

If you carefully observe, integers are also treated as numeric/double. We will learn to create integers in a while. In the meanwhile, we have introduced two new funtions in the above example:

  • class(): returns the class or type
  • is.numeric(): tests whether the variable is of type numeric

Integer

Unless specified otherwise, integers are treated as numeric or double. In this section, we will learn to create variables of the type integer and to convert other data types to integer.

  • create a variable number1 and assign it the value 3
  • check the data type of number1 using class
  • create a second variable number2 using as.integer and assign it the value 3
  • check the data type of number2 using class
  • finally use is.integer to check the data type of both number1 and number2
# create a variable and assign it an integer value
number1 <- 3

# create another variable using as.integer
number2 <- as.integer(3)

# check the data type
class(number1)
## [1] "numeric"
class(number2)
## [1] "integer"
# use is.integer to check data type
is.integer(number1)
## [1] FALSE
is.integer(number2)
## [1] TRUE

Character

Letters, words and group of words are represented by the data type character. All data of type character must be enclosed in single or double quotation marks. In fact any value enclosed in quotes will be treated as character. Let us create two variables to store the first and last name of a some random guy.

# first name
first_name <- "jovial"

# last name
last_name <- 'mann'

# check data type
class(first_name)
## [1] "character"
class(last_name)
## [1] "character"
# use is.charactert to check data type
is.character(first_name)
## [1] TRUE
is.character(last_name)
## [1] TRUE

You can coerce any data type to character using as.character().

# create variable of different data types
age <- as.integer(30) # integer
score <- 9.8          # numeric/double
opt_course <- TRUE    # logical
today <- Sys.time()   # date time

as.character(age) 
## [1] "30"
as.character(score)
## [1] "9.8"
as.character(opt_course)
## [1] "TRUE"
as.character(today)
## [1] "2020-06-10 18:20:48"

Logical

Logical data types take only 2 values. Either TRUE or FALSE. Sich data types are created when we compare two objects in R using comparison or logical operators.

  • create two variables x and y
  • assign them the values TRUE and FALSE respectively
  • use is.logical to check data type
  • use as.logical to coerce other data types to logical
# create variables x and y
x <- TRUE
y <- FALSE

# check data type
class(x)
## [1] "logical"
is.logical(y)
## [1] TRUE

The outcome of comparison operators is always logical. In the below example, we compare two numbers to see the outcome.

# create two numeric variables
x <- 3
y <- 4

# compare x and y
x > y
## [1] FALSE
x < y
## [1] TRUE
# store the result
z <- x > y
class(z)
## [1] "logical"

TRUE is represented by all numbers except 0. FALSE is represented only by 0 and no other numbers.

# TRUE and FALSE are represented by 1 and 0
as.logical(1)
## [1] TRUE
as.logical(0)
## [1] FALSE
# using numbers
as.numeric(TRUE)
## [1] 1
as.numeric(FALSE)
## [1] 0
# using different numbers
as.logical(-2, -1.5, -1, 0, 1, 2)
## [1] TRUE

Use as.logical() to coerce other data types to logical.

# create variable of different data types
age <- as.integer(30) # integer
score <- 9.8          # numeric/double
opt_course <- TRUE    # logical
today <- Sys.time()   # date time

as.logical(age) 
## [1] TRUE
as.logical(score)
## [1] TRUE
as.logical(opt_course)
## [1] TRUE
as.logical(today)
## [1] TRUE

Summary

  • numeric, integer, character, logical and date are the basic data types in R
  • class() or typeof() return the data type
  • is.data_type checks whether the data is of the specified data type
    • is.numeric()
    • is.integer()
    • is.character()
    • is.logical()
    • is.date()
  • as.data_type will coerce objects to the specified data type
    • as.numeric()
    • as.integer()
    • as.character()
    • as.logical()
    • as.date()