Table of Contents
What is a Bubble Chart
Bubble Charts are Scatter charts with variable size of each marker point. Bubble Charts require another dimension for the variable area or radius of each point. Traditionally, most Bubble Charts show a round marker, but we can display most other different marker shapes (squares, diamonds, crosses).
Here are specific variations of this type of chart, first three being described in detail here:
- Simple Bubble Chart – Scatter chart with variable Size of the point markers.
- Labeled Bubble Chart – Bubble chart with additional Category labels for each point.
- Grouped Bubble Chart – multi-series Bubble chart, as pairs of Scatter and Size.
- Adjacency Matrix Bubble Chart – for a measured relationship.
- Quadrant Bubble Chart – Bubble chart with the origin of X/Y axes moved in the middle.
- Polar/Radar Bubble Chart – Bubble chart on a Polar or Radar circular plot.
Steps to Create a Bubble Chart
Start Visual Xtractor or Data Xtractor. Connect to a database. Create or design a SQL query. Run the query and check the results.
- Display and enable the Chart query builder.
- Select a numeric Size, for the variable point radius of this Bubble Charts.
- Select one numeric column as Point Charts – Scatter, for the vertical Y values.
- Select another numeric or text column as Label, for the horizontal X values or labels.
- Select an optional Category, for a Labeled Bubble Chart.
Simple Bubble Chart
A chart with just a Scatter chart selection and a Label is a simple single-series Scatter chart. Add a numeric Size column, and you get a variable radius for each point, you get a Bubble Chart.
The chart is by default monochrome, but could be changed to use multiple colors. Bubbles with negative Y values may be also displayed with a different “down” color.
One single Size chart selection, with nothing else, creates a special Bubble chart, in which the three X, Y and Z (bubble size) values are all the same. The bubble size and transparency can be adjusted.
A different marker shape could be selected for the bubbles. Data labels may be also displayed above or inside the bubbles, with either their X or (by default) Y values.
Bubbles are also displayed by default with Proportional Areas, but you can also select Proportional Radius. Compare the squares for 2 and 4 in the following chart: you can see that the height of 2 if half the height of 4. But the area of 2 is 1/4 the area of 4, so we don’t use here proportional areas. The previous chart has the area of 2 half the area of 4.
The origin of the X/Y axis may be automatically moved in the middle of the chart area, forming a Quadrant Bubble Chart.
Labeled Bubble Chart
Frequent scenarios contain labeled bubbles. When both X and Y are numeric values, you may need a textual label instead to describe each bubble point. Labels may be unique or represent a group or category.
In either case, the way to achieve this is to add another data column as Category, and show this Category in the data labels instead. The chart below shows a multi-color Bubble Chart with this new Category values as visible data labels:
Grouped Bubble Chart
More than one pair of Scatter and Size selections – with each Size after its related Scatter column – create a multi-series Grouped Bubble Chart. By default, each series gets its own color and marker style, but both can be changed.
Customize your Bubble Chart
- Show the Bubble chart as multi-color, with each bubble getting a different color.
- Change the default bubble markers with squares.
- Show data labels, inside the bubbles.
- Switch to a 3D view and show a Quadrant Bubble Chart.
- If multi-series, continue by using the legend items to hide some series.
- Creating a Bubble Chart in Data Xtractor or Visual Xtractor is fast and easy: add to a Scatter chart a numeric Size, which will translate into a variable radius for each point.
- Add a Category column for labeled bubbles.
- Show the chart as a Quadrant Bubble Chart.
- Use both initial coordinates with text, for a Dependency Crosstab Bubble Chart.
- All builtin powerful features of these chart type are common to most other charts: filtering series through the legend items, interactivity, monochrome or grayscale colors, rich axis and data label selections etc.
- Switch to another builtin chart theme, or customize your own, for any possible color or other styles.