Assigning variables

Usually you want to use objects like vectors more than once. In order to save the trouble of retyping and recreating them all the time we would like to save them somewhere and reuse them later.

To do this we can assign them to a variable name. R uses the special arrow operator <- for assigning values to a variable. The arrow is simply the combination of a smaller-than character (<) and a minus sign (-).

Let’s take a look at an example, in which we assign a numeric vector to a variable named numbers:

Input
numbers <- c(1, 2, 3, 4, 5, 6, 7, 8, 9)

Now we can use the variable’s name below to see its contents:

Input
numbers
Output
[1] 1 2 3 4 5 6 7 8 9

Note, that when we assign something to a variable that already exists, it gets overwritten. All previous contents are automatically removed:

Input
numbers <- c(10, 11, 12, 13)
numbers
Output
[1] 10 11 12 13

Once you have defined a variable you can use it just like you would use the underlying vector itself. In the following example we create two numeric vectors and assign them to the variables low and high. Then we use these variables and concatenate the two vectors into a single one and assign it to the variable named sequence. Finally we call the sequence variable and inspect its contents:

Input
low <- c(1, 2, 3)
high <- c(4, 5, 6)
sequence <- c(low, high)
sequence
Output
[1] 1 2 3 4 5 6

As you can see, the vectors 1, 2, 3 and 4, 5, 6 stored in the variables low and high, were combined into a single vector that is now the the content of the variable sequence.

Create variables through assignments