**Table of Contents**

In a data-analysis system like Rax, the most important use of the graphical procedures will be visualizing the data. To make it easy, the standard Rax distribution contains a plotting library with various chart types. To use the plotting library, include it in your script:

%include __EXE_PATH__ "rx_GraphicalEngine/SimpleCharts.rax";

A bar plot can be generated by using the ``barplot`

function:

`barplot data,width,height;

The `data`

parameter is a set of tuples of the
following type:

{[$:series, $:category, &:value]}

where `series`

is the name of the series to which a
given data point belongs, `category`

is the name of the
category to which the data point belongs and `value`

is
the value in the data point. For example, the following Rax program:

%include "SimpleCharts.rax"; {[$:vehicleType, $:dayOfWeek, &:number]} : data := { ["cars", "Monday", 1.0], ["cars", "Tuesday", 3.0], ["cars", "Wednesday", 6.0], ["cars", "Thursday", 4.0], ["cars", "Friday", 9.0], ["suvs", "Monday", 4.0], ["suvs", "Tuesday", 4.0], ["suvs", "Wednesday", 6.0], ["suvs", "Thursday", 6.0], ["suvs", "Friday", 16.0], ["trucks", "Monday", 2.0], ["trucks", "Tuesday", 5.0], ["trucks", "Wednesday", 4.0], ["trucks", "Thursday", 5.0], ["trucks", "Friday", 12.0], }; `barplot data, 600.0, 400.0;

Will produce the chart in Figure 16.1, “A bar plot generated by Rax”.