Functions are actions we can perform. R provides a number of functions, and you’ve actually been using a few of them even though you maybe didn’t realize!

We *call*, or use, these functions by stating the name of the function and following it with an opening and closing parentheses: ie. `functionName()`

. In addition, between the parenthesis, we usually pass in an *argument*, or a value that the function uses to conduct an action, i.e. `functionName(value)`

.

Does that syntax look a little familiar? When we have used `print()`

we’re calling the `print`

function. When we made a vector, we actually used the combine `c()`

function! Let’s see `print()`

and some real functions in action!

sort(c(2,4,10,5,1)); # Outputs c(1,2,4,5,10) length(c(2,4,10,5,1)); # Outputs 5 sum(5,15,10) #Outputs 30

Let’s look at each of the lines above:

- On the first line, the
`sort()`

function is called with a parameter of the vector`c(2,4,10,5,1)`

. The result is a sorted vector`c(1,2,4,5,10)`

with the values in ascending order. - On the second line, we called a function we’ve seen before:
`length()`

and it returned the value 5 because there were five items in the vector. - On the third line, we called a function
`sum()`

which added up all of the arguments we passed to it.

Understanding how to call a function and what arguments it needs is a fundamental part of leveraging R as a tool to conduct analysis. Let’s practice calling some useful functions!

### Instructions

**1.**

The `unique()`

function takes a vector argument and returns a vector with only the unique elements in that vector (removing all duplicates).

- Call this function and pass in the argument
`data`

. - Save that result inside a variable named
`unique_vals`

- Print
`unique_vals`

variable so you can see what is inside the vector with only unique values.

**2.**

Get the `sqrt()`

square root of the number 49 by calling the function with the specified argument. Save the result inside a variable named `solution`

.

Print the `solution`

variable so you can see confirm `sqrt()`

computed the square root correctly.

**3.**

The `floor()`

function rounds a decimal down to the next integer, and the `ceiling()`

function will round up to the next integer. Call both functions on the number 3.14, and save each result inside two new variables you create: `round_down`

and `round_up`

respectively.

Print both variables so you can see what’s in them!

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