Variables in R - JournalDev

Variables in R are the same as the notion of variables in any other programming language. Variable is a name we assign for the storage space location that stores our data. A variable in R can be of any datatype, simple or complex. There are certain rules and conventions when working with variables in R.

Variables in R – Naming Rules

The name of a variable is known as an identifier. Not every string can be an identifier in R.

Variables in R are case sensitive. The names Car, car and CAR are all treated as different variables in spite of the same spelling.
Variables can never begin with symbols or numbers. 1car and &car are not valid variable names.
Variable names can begin with a period (.). However, if a name starts with a period, it must be followed by a letter instead of a number.
For defining complex names, period or underscore can be used as the seperator. For example, a.one and a_one are both valid variable names.
However, since underscore was used as an assignment operator in earlier versions of R, a period is preferred over underscore.
Variable names can never contain a blank space.

Variable Assignment

In the previous post on data types in R, we have introduced the assignment operator in R <-. This is knows as the gets operator. When we write a statement a <- b, it can be verbally expressed as, a gets the value of b.

Never put a space between the less than and hyphen in our gets operator. The statement a <- 10 is an assignment statement, whereas a < -10 is interpreted as a less than minus 10, resulting in a Boolean output.

In addition to the gets operator, there is also the right assignment operator, that is a reverse of gets ->. The statement 10 -> a is equivalent to a <- 10.

Also, the equals sign can be used for assignment of variables in R just like C or C++. The statement a = b is a valid one.

Some Useful Tips with Variables

When working with complex projects, it sometimes gets tedious to remember all the variable names. Therefore you can type in ls() in the console to get a list of all active variables.
To remove a specific variable from the environment the command is rm(<variablename>). The space gets freed and can be reassigned to another variable now. To remove a variable named x, simply type in rm(x).
The code snippet below displays the ls() utility. All the variables and function names in the enivornment get displayed.

> ls()
 [1] "a"          "a_one"      "average"    "b"          "c"          "code"      
 [7] "division"   "elfunction" "fs"         "myname"     "myname2"    "myvector"  
[13] "name

Suppose that we need to remove a variable named average, it can be done by typing in rm(average) . Using ls again, we see that the variable in no longer in the environment.

> rm(average)
> ls()
 [1] "a"          "a_one"      "b"          "c"          "code"       "division"  
 [7] "elfunction" "fs"         "myname"     "myname2"    "myvector"   "name"