2.2 Assignment operator

For instance, instead of adding 3 + 5, we can assign those values to objects and then add them.

# assign 3 to a
a <- 3
# assign 5 to b
b <- 5

# what now is a
a
# what now is b
b
# Add a and b
a + b

<- is the assignment operator. It assigns values on the right to objects on the left. So, after executing x <- 3, the value of x is 3. The arrow can be read as 3 goes into x. You can also use = for assignments but not in all contexts so it is good practice to use <- for assignments. = should only be used to specify the values of arguments in functions, see below.

In RStudio, typing Alt + - (push Alt, the key next to your space bar at the same time as the - key) will write <- in a single keystroke.

To view which objects we have stored in memory, we can use the ls() command

ls()

To remove objects we can use the rm() command

rm(a)

2.2.1 Exercise

• What happens if we change a and then re-add a and b?
• Does it work if you just change a in the script and then add a and b? Did you still get the same answer after they changed a? If so, why do you think that might be?
• We can also assign a + b to a new variable, c. How would you do this?