R is a popular programming language used for statistical computing and graphical presentation.
Its most common use is to analyze and visualize data.
R was started by professors Ross Ihaka and Robert Gentleman as a programming language to teach introductory statistics at the University of Auckland.[9] The language was inspired by the S programming language, with most S programs able to run unaltered in R.[6] The language was also inspired by Scheme’s lexical scoping, allowing for local variables.[1]
The name of the language, R, comes from being both an S language successor as well as the shared first letter of the authors, Ross and Robert.
To install R, go to https://cloud.r-project.org/ and download the latest version of R for Windows, Mac or Linux.
When you have downloaded and installed R, you can run R on your computer.
After installation of R
If you type 5 + 5, and press enter, you will see that R outputs 10.
5+5## [1] 10To output text in R, use single or double quotes:
"Hello World!"## [1] "Hello World!"To output numbers, just type the number (without quotes):
5## [1] 510## [1] 1025## [1] 25To do simple calculations, add numbers together:
10-7## [1] 3Variables are containers for storing data values.
R does not have a command for declaring a variable. A variable is created the moment you first assign a value to it. To assign a value to a variable, use the <- sign (or = sign). To output (or print) the variable value, just type the variable name:
name <- "Bijay Lal Pradhan"
age <- 50
name # output "Bijay Lal Pradhan"## [1] "Bijay Lal Pradhan"age # output 50## [1] 50You can also concatenate, or join, two or more elements, by using the paste() [or cat] function.
To combine both text and a variable, R uses comma (,):
text <- "awesome"
paste("R is", text)## [1] "R is awesome"A variable can have a short name (like x and y) or a more descriptive name (age, carname, total_volume). Rules for R variables are: A variable name must start with a letter and can be a combination of letters, digits, period(.) and underscore(). If it starts with period(.), it cannot be followed by a digit. A variable name cannot start with a number or underscore () Variable names are case-sensitive (age, Age and AGE are three different variables) Reserved words cannot be used as variables (TRUE, FALSE, NULL, if…)
Basic data types in R can be divided into the following types:
numeric - (10.5, 55, 787)
integer - (1L, 55L, 100L, where the letter “L” declares this as an integer)
complex - (9 + 3i, where “i” is the imaginary part)
character (a.k.a. string) - (“k”, “R is exciting”, “FALSE”, “11.5”)
logical (a.k.a. boolean) - (TRUE or FALSE)
We can use the class() function to check the data type of a variable:
# numeric
x <- 10.5
class(x)## [1] "numeric"# integer
x <- 1000L
class(x)## [1] "integer"# complex
x <- 9i + 3
class(x)## [1] "complex"# character/string
x <- "R is exciting"
class(x)## [1] "character"# logical/boolean
x <- TRUE
class(x)## [1] "logical"
1.3.0.1 Comments
Comments can be used to explain R code, and to make it more readable. It can also be used to prevent execution when testing alternative code.
Comments starts with a #. When executing code, R will ignore anything that starts with #.
This example uses a comment before a line of code: