# # 1. Hello World!

Here's an R code chunk that prints the text 'Hello world!'.

# # 2. Creating sequences

We just learned about the `c()` operator, which forms a vector from its arguments. If we're trying to build a vector containing a sequence of numbers, there are several useful functions at our disposal. These are the colon operator `:` and the sequence function `seq()` .

## #`seq` function: `seq(from, to, by)`

To learn more about a function, type `?functionname` into your console. E.g., `?seq` pulls up a Help file with the R documentation for the `seq` function.

# # 3. Cars data

We'll look at data frame and plotting in much more detail in later classes. For a previous of what's to come, here's a very basic example.

For this example we'll use a very simple dataset. The `cars` data comes with the default installation of R. To see the first few columns of the data, just type `head(cars)` .

We'll do a bad thing here and use the `attach()` command, which will allow us to access the `speed` and `dist` columns of `cars` as though they were vectors in our workspace.

## # (a) Calculate the average and standard deviation of speed and distance.

We can easily produce a histogram of stopping distance using the `qplot` function.

## # (b) Produce a histogram of stopping distance using the `hist` function with 10 bins.

The `qplot(x,y,...)` function can also be used to plot a vector `y` against a vector `x` . You can type `?qplot` into the Console to learn more about the basic qplot function.