Setting and Viewing Bubble Plots

The bubble style lets you add additional layers of information to your XY plot. One layer of information is available by mapping the bubble diameter to a scalar field. Another layer of information comes from mapping the bubble color to a scalar field.



Relationship between Pressure versus Tangential Velocity	Bubble size adds Radial Velocity	Bubble color adds Temperature

You are advised not to use the bubble style for data sets with more than a few hundred data points. The large number of symbols would render the plot difficult to read. If you expect a high proportion of overlapping bubbles then you can apply transparency to the bubbles so that bubbles in the background are still visible.

To configure the bubble style for an XY plot to which you have already added X and Y Types:

In the data set sub-node of the Y Type node of the plot, set the Styles property to Bubble.
Select the Bubble Style sub-node of the data set, and specify properties of the shapes:
1. Decide on the shape of the objects using the Shape property.
2. Decide on the appearance of the object borders using the Border Width and Border Color properties.
3. Set the level of transparency with the Opacity property. Having some transparency lets you view overlapping symbols easier.
4. In the Color Fill Mode property, choose from among a variable color, which lets you add a fourth (scalar) variable to the plot, a constant fill for the shapes, or no fill.
Determine how the symbols vary in size by editing the properties of the Size Scaling Data node:
1. Set the range of symbol sizes, in pixels, using the Minimum symbol size and Maximum symbol size properties. You can use these settings for reverse scaling, that is, enter the largest value as the minimum and the smallest value as the maximum.
  - To set up a typical scatter plot with these symbols, set the minimum and maximum sizes to the same value. The size legend disappears from the plot display.
2. The Scale mode property offers the following different methods for calculating the area of the symbols. As you decide which is best, see the Scale mode property description in Bubble Plot Objects Reference.
  - Width (Linear)—the default setting, uses a linear increase in size.
  - Logarithmic—uses an exponential variation in size.
  - Area (Square Root)—creates the most visually natural differentiation between bubble sizes. This option is recommended if all your data values are positive.
    If you choose Logarithmic or Area (Square Root), you can also decide whether to display negative values by activating or deactivating the Show negative symbol sizes option. The symbols that represent negative values contain an "X" to differentiate them from the positive values.
3. Decide on the data range:
  - To include all the solution data, leave Data range mode set at Auto.
  - To include only a subset of the data, set values for Manual data range min and Manual data range max.
    It is possible to set minimum and maximum values outside of the automatically calculated data range. This capability is useful for making the ranges of multiple data sets consistent.
4. Select the scalar field by selecting the Scalar Function sub-node of the Size Scaling Data node and setting the Field Function property.
To use the bubble color as an information layer:
1. In the properties of the Bubble Style node, set Color Fill Mode to Variable.
2. Select values for color properties such as:
  - Color Map—lets you customize the use of colors in the bubble plot, mapping colors to values. There are pre-defined color maps that are especially suitable for bubble plots.
  - Levels—sets the number of levels into which to divide the range of data.
  For more details, see Color Scaling Data Properties.
3. Set the scalar field by selecting the Scalar Function sub-node and setting the Field Function property.
If your plot uses more than one input part, do the following to display them effectively:
1. To ensure that the scaling is consistent for all parts in the plot:
  1. Multi-select all Size Scaling Data nodes.
  2. Right-click and select Reset manual data extents.
  3. Right-click and select Edit, and use the multi-edit dialog to set the minimum and maximum symbol sizes and data ranges uniformly for all the parts.
  4. Repeat the above procedure for the Color Scaling Data node.
2. To have only one part's legend appear in the plot, multi-select the data series nodes for all the other parts and deactivate Show legend entry.

For more information about bubble style options, see Bubble Plot Objects Reference.