Plotting with qplot and R

Suppose that we want to visualize some of the variables in the built-in datasets. A dataset can contain different kinds of variables, as discussed previously. Here, the climate data includes numerical data, such as the temperature, and categorical data, such as hot or cold. In order to visualize and correlate different kinds of data, we need to understand the nomenclature of the dataset. We'll load a data file and understand the structure of the dataset and its variables by using the qplot and R base package. Let's begin by executing the following steps:

1. Plot the temperature variable from the airquality dataset, with hist(airquality$Temp) .
   

  Take a look at the following output screenshot:

2. Use qplot (which is part of the ggplot2 package) to plot a graph, using the same variables.

3. Type the qplot(airquality$Temp) command to obtain the output, as shown in the following screenshot: