## Shading and coloring your graph

You can shade and color your graphs using the `polygon()`

command. To use the `polygon()`

command, you must specify the horizontal and vertical axis limits, but you must also include the *x* and *y* variables as the middle arguments.

Let's create a quadratic curve and shade under it with a light green selected from the Hexadecimal Color Chart:

x <- 1:100y <- 3*x^2 + 2*x + 7plot(x, y)lines(x, y)polygon(cbind(c(min(x), x, max(x)), c(min(y), y, min(y))), col="#00CC66")

Here is the graph:

Using this approach, the
`polygon()`

command shades under the curve, between the minimum and maximum values of the *x* variable and below the *y* variable. The syntax involving `cbind()`

is an elegant way of including the relevant limits.

The following example is more complex. It uses the `rnorm()`

command to simulate values from a normal distribution, with a given mean and standard deviation. By default, random values with a mean of 0 and a standard deviation of 1 are produced. For...