Combination charts let you combine two or more chart types in a single chart, for example, a column chart series and a line chart series. This is done either to highlight specific data series by rendering, or to mix different types of data series on the same chart. There are two types of combination charts possible in FusionCharts.

The first type, called Single Y-axis combination charts, have a single y-axis and all the data series conform to it. Some charts in this category are MSCombi2D.swf, MSCombi3D.swf, MSColumnLine3D.swf, and so on. As an example, if you wish to plot the actual revenue versus the projected revenue on a chart, as both the series have the same unit (currency) and magnitude, we plot them against the same axis. However, as the focus is on the actual revenue, it should be plotted using column or area, and the projected revenue can be plotted using lines to show it as guidance.

The second type, called Dual Y-axes combination charts, have two y-axes, each having its own units and magnitude. These charts have the abbreviation DY in their name, for example, MSCombiDY2D.swf or MSColumn3DLineDY.swf. Consider a chart where you are plotting the revenue of a company versus the units (quantity) sold. As both the series represent different units, they need to be plotted on different axes. The primary axis can represent the sales, and the second used for units sold. Conventionally, you would represent the sales using columns plotted against the primary axis on the left side of the chart, and the units sold using lines plotting against the secondary axis on the right side of the chart.

Let us build an example of both these charts.