R Tutorial
R Data Interfaces
R Charts & Graphs
R Statistics Examples
R Useful Resources
Selected Reading
- R - Data Reshaping
- R - Packages
- R - Data Frames
- R - Factors
- R - Arrays
- R - Matrices
- R - Lists
- R - Vectors
- R - Strings
- R - Functions
- R - Loops
- R - Decision Making
- R - Operators
- R - Variables
- R - Data Types
- R - Basic Syntax
- R - Environment Setup
- R - Overview
- R - Home
R Data Interfaces
- R - Database
- R - Web Data
- R - JSON Files
- R - XML Files
- R - Binary Files
- R - Excel Files
- R - CSV Files
R Charts & Graphs
R Statistics Examples
- R - Chi Square Tests
- R - Survival Analysis
- R - Random Forest
- R - Decision Tree
- R - Nonlinear Least Square
- R - Time Series Analysis
- R - Analysis of Covariance
- R - Poisson Regression
- R - Binomial Distribution
- R - Normal Distribution
- R - Logistic Regression
- R - Multiple Regression
- R - Linear Regression
- R - Mean, Median & Mode
R Useful Resources
Selected Reading
- Who is Who
- Computer Glossary
- HR Interview Questions
- Effective Resume Writing
- Questions and Answers
- UPSC IAS Exams Notes
R - Variables
R - Variables
A variable provides us with named storage that our programs can manipulate. A variable in R can store an atomic vector, group of atomic vectors or a combination of many Robjects. A vapd variable name consists of letters, numbers and the dot or underpne characters. The variable name starts with a letter or the dot not followed by a number.
| Variable Name | Vapdity | Reason |
|---|---|---|
| var_name2. | vapd | Has letters, numbers, dot and underscore |
| var_name% | Invapd | Has the character % . Only dot(.) and underscore allowed. |
| 2var_name | invapd | Starts with a number |
.var_name, var.name |
vapd | Can start with a dot(.) but the dot(.)should not be followed by a number. |
| .2var_name | invapd | The starting dot is followed by a number making it invapd. |
| _var_name | invapd | Starts with _ which is not vapd |
Variable Assignment
The variables can be assigned values using leftward, rightward and equal to operator. The values of the variables can be printed using print() or cat() function. The cat() function combines multiple items into a continuous print output.
# Assignment using equal operator.
var.1 = c(0,1,2,3)
# Assignment using leftward operator.
var.2 <- c("learn","R")
# Assignment using rightward operator.
c(TRUE,1) -> var.3
print(var.1)
cat ("var.1 is ", var.1 ,"
")
cat ("var.2 is ", var.2 ,"
")
cat ("var.3 is ", var.3 ,"
")
When we execute the above code, it produces the following result −
[1] 0 1 2 3 var.1 is 0 1 2 3 var.2 is learn R var.3 is 1 1
Note − The vector c(TRUE,1) has a mix of logical and numeric class. So logical class is coerced to numeric class making TRUE as 1.
Data Type of a Variable
In R, a variable itself is not declared of any data type, rather it gets the data type of the R - object assigned to it. So R is called a dynamically typed language, which means that we can change a variable’s data type of the same variable again and again when using it in a program.
var_x <- "Hello"
cat("The class of var_x is ",class(var_x),"
")
var_x <- 34.5
cat(" Now the class of var_x is ",class(var_x),"
")
var_x <- 27L
cat(" Next the class of var_x becomes ",class(var_x),"
")
When we execute the above code, it produces the following result −
The class of var_x is character
Now the class of var_x is numeric
Next the class of var_x becomes integer
Finding Variables
To know all the variables currently available in the workspace we use the ls() function. Also the ls() function can use patterns to match the variable names.
print(ls())
When we execute the above code, it produces the following result −
[1] "my var" "my_new_var" "my_var" "var.1" [5] "var.2" "var.3" "var.name" "var_name2." [9] "var_x" "varname"
Note − It is a sample output depending on what variables are declared in your environment.
The ls() function can use patterns to match the variable names.
# List the variables starting with the pattern "var". print(ls(pattern = "var"))
When we execute the above code, it produces the following result −
[1] "my var" "my_new_var" "my_var" "var.1" [5] "var.2" "var.3" "var.name" "var_name2." [9] "var_x" "varname"
The variables starting with dot(.) are hidden, they can be psted using "all.names = TRUE" argument to ls() function.
print(ls(all.name = TRUE))
When we execute the above code, it produces the following result −
[1] ".cars" ".Random.seed" ".var_name" ".varname" ".varname2" [6] "my var" "my_new_var" "my_var" "var.1" "var.2" [11]"var.3" "var.name" "var_name2." "var_x"
Deleting Variables
Variables can be deleted by using the rm() function. Below we delete the variable var.3. On printing the value of the variable error is thrown.
rm(var.3) print(var.3)
When we execute the above code, it produces the following result −
[1] "var.3" Error in print(var.3) : object var.3 not found
All the variables can be deleted by using the rm() and ls() function together.
rm(pst = ls()) print(ls())
When we execute the above code, it produces the following result −
character(0)Advertisements