# Vectors

### Vectors

Watch this video:

### Create a vector

In the chunk below, create a vector that contains the integers from one to ten. Use the `c()`

function.

`c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)`

`:`

If your vector contains a sequence of contiguous integers, you can create it with the `:`

shortcut. Run `1:10`

in the chunk below. What do you get? What do you suppose `1:20`

would return?

```
1:10
1:20
```

`[]`

You can extract any element of a vector by placing a pair of brackets behind the vector. Inside the brackets place the number of the element that youâ€™d like to extract. For example, `vec[3]`

would return the third element of the vector named `vec`

.

Use the chunk below to extract the fourth element of `vec`

.

```
<- c(1, 2, 4, 8, 16)
vec 4] vec[
```

### More `[]`

You can also use `[]`

to extract multiple elements of a vector. Place the vector `c(1,2,5)`

between the brackets below. What does R return?

```
<- c(1, 2, 4, 8, 16)
vec c(1,2,5)] vec[
```

### Names

If the elements of your vector have names, you can extract them by name. To do so place a name or vector of names in the brackets behind a vector. Surround each name with quotation marks, e.g. `vec2[c("alpha", "beta")]`

.

Extract the element named gamma from the vector below.

```
<- c(alpha = 1, beta = 2, gamma = 3)
vec2 "gamma"] vec2[
```

### Vectorised operations

Predict what the code below will return. Then look at the result.

Good job! Like many R functions, Râ€™s math operators are vectorized: theyâ€™re designed to work with vectors by repeating the operation for each pair of elements.

### Vector recycling

Predict what the code below will return. Then look at the result.

Good job! Whenever you try to work with vectors of varying lengths (recall that `1`

is a vector of length one), R will repeat the shorter vector as needed to compute the result.