How to Store and Calculate Values in R
Using R as a calculator is very interesting but perhaps not all that useful. A much more useful capability is storing values and then doing calculations on these stored values.
Try the following:
> x <- 1:5 > x  1 2 3 4 5
In these two lines of code, you first assign the sequence 1:5 to a variable called x. Then you ask R to print the value of x by typing x in the console and pressing Enter.
In R, the assignment operator is <-, which you type in the console by using two keystrokes: the less-than symbol (<) followed by a hyphen (-). The combination of these two symbols represents assignment.
In addition to retrieving the value of a variable, you can do calculations on that value. Create a second variable called y, and assign it the value 10. Then add the values of x and y, as follows:
> y <- 10 > x + y  11 12 13 14 15
The values of the two variables themselves don’t change unless you assign a new value. You can check this by typing the following:
> x  1 2 3 4 5 > y  10
Now create a new variable z, assign it the value of x+y, and print its value:
> z <- x + y > z  11 12 13 14 15
Variables also can take on text values. You can assign the value "Hello" to a variable called h, for example, by presenting the text to R inside quotation marks, like this:
> h <- "Hello" > h  "Hello"
You must present text or character values to R inside quotation marks — either single or double. R accepts both. So both h <- "Hello" and h <- 'Hello' are examples of valid R syntax.
In Using vectors, you use the c() function to combine numeric values into vectors. This technique also works for text. Try it:
> hw <- c("Hello", "world!") > hw  "Hello" "world!"
You can use the paste() function to concatenate multiple text elements. By default, paste() puts a space between the different elements, like this:
> paste("Hello", "world!")  "Hello world!"