Chart tool - an introduction

Getting Started with Charting Tools

The Charting Tool is a simple, yet powerful, way to create charts and graphs of data in the system.

To start a new chart, choose any dataset and click the "Make a Chart" button from the dataset page or "Create chart" from the Actions menu, which will start a chart with that dataset loaded. You can also base a new chart on an existing snapshot.

If you base a chart on a snapshot, rules will be defined for you that match those used in the snapshot. Otherwise, the chart tool will create an initial default chart with the dataset.

Types of Charts

There are four chart types - Scatter Plot, Line, Bar and Pie Charts.

Scatter Plot Charts

Scatter plot charts (sometimes called X-Y plot) are useful for showing the relationship between two different sequential attributes. The attribute for the X axis can be either numbers or dates, and the attribute for the Y axis must be numbers.

Line Charts

Line charts track changes over a set of data. Just like scatter plots, both axes must be sequential, and only numbers on the Y axis.

Bar Charts

Bar charts (sometimes called column charts) compare two data attributes, but unlike scatter and line, the X axis can be either "categorical" or sequential. This means that text attributes can be used as "bins" to show data. If the X axis attribute is sequential, it may be grouped. The Y axis attribute must be numbers.

The user interface choices for scatter plots, line charts and bar charts are very similar. First, choose which attribute to use on the X (horizontal) axis. You can group records along this axis to aggregate values together, or leave them ungrouped to see all records. For the Y (vertical) axis, pick another attribute. You can group here as well with basic math functions like average, sum, minimum and maximum. You can display all the records in the dataset, or filter them with a "where" clause. This is especially useful with multiple series on the chart, which you can add with the "plus" button to the right of your rule. This adds another series, which can show similar or different information than the first, and can be set to its own style. If you have multiple series showing similar data, you can merge the axis labels into one so they have the same range. You can also show one series with an axis on the left (the default) and put another series' axis labels on the right. You can select which side to use when setting the style for the series.

Pie Charts

Pie charts are useful for showing parts of a whole. You need at least on numeric attribute in your dataset, of which the pie will show the distribution. This distribution will be grouped by common values of another attribute. You can include all records in the pie chart, or make a "where" statement to limit the chart to just some of the records.

If you are ready to make a snapshot of your chart, choose "Create snapshot" from the action menu in the upper right. This will create a snapshot of your chart as it is at that moment. You can continue to work, and make multiple snapshots.

You can also examine the legend as you go. Click on the drawer tab on the right edge of the chart tool to slide it out. This legend will be visible on any snapshots you create. Note that pie charts have the legend markers on the chart and do not have a separate legend.