Bubble Charts

Introduction

A bubble chart uses relative magnitude visualization for showing data that is composed of value pairs. Both values in a pair can vary freely. The data must consist of 2 columns grouped together. These column are:

The order of the columns is significant.

There are three possible ways for relative magnitude visualization. These ways are relative color, paint and size. All ways can be used simultaneously. A color or paint channel can be given, but not used for relative magnitude visualization. Bubble chart is a variation of a scatter chart.

Data Model

Mandatory channels: 2 value channels grouped together, at least one of color, paint or size channels

Optional channels: other groups of 2 value channels, alt, color, label, paint, shape, stroke, url

When color, paint or size channels are given for relative magnitude visualization, the values in the channels will be compared with each other for getting the relative values that are used for visualization. For example, a paint channel used for visualization could be given as: 

<column type="paint" dataType="date" dataFormat="yyyy-MM-dd">
  <element>1999-12-03</element>
  <element>1999-11-15</element>
  <element>1999-10-20</element>
  <element>1999-09-02</element>
</column>

If a channel is used for relative magnitude visualization, another channel of the same type is used for visualization too. This means that the paint channels have to have the same data type or at least data types that are comparable with each other. For example, if a paint channel given above is used, other possible paint channels that are given have to have the data type of date. If a special visualization scale within a series tag is used for a specific value channel, the restriction of the same data type is removed from the corresponding visualization, which is paint in this example, channel.

Note that other optional channels but value have an effect on grouped value channels.

Required Attributes

For using relative magnitude visualization, certain attributes have to be given in addition to the data channels for visualization. The attributes are given in the plot tag and the attributes are:

If the attributes are not given, relative magnitude visualization for the data channels is not performed.

Examples

Symbol size magnitude visualization.
Symbol size and edge and fill color magnitude visualizations.
Two series with different symbols.

See also

Scatter Chart can represent similar data.

Relative magnitude visualization can also be done with other charts. However, all charts are not able to use all visualization ways.