Variable is memory location for storing values in any programming language including R. In R Program variable names are assigned with symbol left arrow (<-) or right arrow (->) on either side or with equal to (=) symbol.
Variables are of 2 types based on their usage across the function
- Global Variable – Accessible from outside a function and is assigned with the symbol (<<-)
- Local Variable – Accessible only from inside a function and is assigned with the symbol (<-)
Based on the type of values they contain; variables can be classified as:
These variable have a binary value [1,0], [TRUE, FALSE], [YES, NO].
R has mostly numeric integer variable for declaration
Y = 7.5321
These variables are defined in quotation marks and contains either numeric or character values
These variables contain both numeric and character values with more than one value
Naming Convention of Variable
- A variable name consists of numbers, letters, dot, underline characters
- A variable name starts with a letter or a dot not followed by a number
- A variable name cannot start with a number.
- A variable name cannot start with an underscore character.
Create a variable
Create a dataset
Stadium <- c (“Wankhede”, “Eden Gardens”)
Audience <- c (80000, 90000)
Ticket <- c (3000, 5000)
Df <- data.frame (Stadium, Audience, Ticket)
Add a new variable: Df$stands <- c( 15, 12)
Rename an existing variable: Df$Arena <- Df$Stand
Delete a variable: DF$Arena <- NULL
Constants are assigned with values which cannot be changed. These are of 2 types (i) Numeric Constant (ii) Character Constant
Numeric Constant: They can be of type integer, double, complex
Character Constant: They are represented by using single quotes or double quotes.
Typeof () function is used to identify the type of constant
Typeof(12) – “double”
Typeof(12L) – “integer”
Typeof(“12) – “character”