All capabilities of a chart are accessible after creating the chart object. A chart is created by specifiying the appropriate type (i.e. ScatterPlot, LinePlot, etc). The information about the data is passed as an argument to the object constructor. See more information about chart types.

A chart object is created by the constructor of the chart of the selected type class. The constructor syntax is as follows:

PlotType(dataObject)

where PlotType should ne substituted for the name of the appropriate plot class. The dataObject parameter specifies the data object which should be used for creating the plot.

For each chart object the following methods are available:

show()

setTitle(name)

getTitle()

getJFreeChart()

d = Data('tableName', ['x', 'y'] )
ScatterPlot(d).show()
                

There is also a simpler way of creating charts ad-hoc. It is particulary convenient for creating a single chart, without creating a Data object.

ScatterPlot('tableName', ['x', 'y']).show()
                

The three main chart types are described below.

Type 1 - 2D charts

Classes

The following 2D plot classes can be used:

• ScatterPlot
• LinePlot

Data preparation

The syntax for the Data constructor for use with 2D charts is the following:

Data(tableName, [x_column, y_column])

or

Data(tableName, [series_column_name, x_column, y_column])

Table 11.2.  Description of Data constructor parameters for 2D charts

Parameter	Description
series_name_column	the name of the containing the names of series to which the the coordinate pairs belong
x_column	the name of the column with the x coordinate values
y_column	the name of the column with the y coordinate values

Example 11.9. Creating a 2D plot

table 'scatter_plot':
    s  x     y
    a  0     0
    b  0     0.5
    a  0.5   0.25
    b  0.5   1
    a  1     1
    a  1.5   2.25
    b  1     1.5
    b  1.5   2
    a  2     4
    b  2     2.5

d = Data('scatter_plot', ['s', 'x', 'y'])
ScatterPlot(d).show()         
    

Figure 11.9. 2 series scatter plot

Type 2 - 3D charts

Classes

The following 3D plot classes can be used:

• BubblePlot

Data preparation

The syntax for the Data constructor for use with 3D charts is the following:

Data(tableName, [x_column, y_column, z_column])

or

Data(tableName, [series_column_name, x_column, y_column, z_column])

Table 11.3.  Description of Data constructor parameters for 3D charts

Parameter	Description
series_name_column	the name of the containing the names of series to which the the coordinate pairs belong
x_column	the name of the column with the x coordinate values
y_column	the name of the column with the y coordinate values
z_column	the name of the column with the z coordinate values

Example 11.10. Creating a bubble plot

table 'bubble_plot':
    x    y    z
    1    2    0.3
    1.5  1.5  0.5
    2    1    0.1
    2.5  2.7  0.2
    3    3    0.2
    3.5  1.8  0.4
    4    2    0.15

d = Data('bubble_plot', ['x', 'y', 'z'])
BubblePlot(d).show()       
    

Figure 11.10. Bubble plot

Note

The z-axis information is encoded in the size og the bubbles.

Type 3 - nominal data charts

Classes

The following plot classes can be used with nominal data:

• CategoryPlot (bar chart)
• PiePlot
• ScatterCategory3DPlot (requires Java3D to be installed)
• LineCategory3DPlot (requires Java3D to be installed)
• Bar3DPlot (requires Java3D to be installed)
• Pie3DPlot (requires Java3D to be installed)

Data preparation

The syntax for the Data constructor for use with 3D nominal charts is the following:

Data(tableName, [group_name_column, numeric_value_column])

Table 11.4.  Description of Data constructor parameters for 3D charts

Parameter	Description
group_name_column	the name of the column containing the group names
numeric_values_column	the name of the column with the values for each group

Example 11.11. Creating a category plot

table 'category_plot':
    c2        c3
    'high'    55
    'high'    32
    'high'    40
    'medium'  24
    'medium'  28
    'medium'  20
    'low'      4
    'low'      8
    'low'     11

d = Data('category_plot', ['c2', 'c3'])
CategoryPlot(d).show()     
    

Figure 11.11. Category plot

It is possible to plot more than one chart on the same display with common x and y axes. The range of common axes will be set to show all the values from the grouped charts.

It is possible to group horizontally (common x axis) as well as vertically (common y axis)

Syntax:

CombinedVerticalXYPlot(xyplot1, xyplot2, ..., xyplotN)

CombinedHorizontalXYPlot(xyplot1, xyplot2, ..., xyplotN)

Example 11.12. Grouping plots

table 'table_A':
    a1  a2
    1   2
    3   4
                    
table 'table2':
    x   y
    1   2
    3   4
    
p1 = ScatterPlot('table_A', ['a1', 'a2'])
p2 = LinePlot('table2', ['x', 'y'] )
CombinedVerticalXYPlot(p1, p2).show()
    

Figure 11.12. Grouped plots

This subsection describes some useful capabilities of the JFreeChart interface.

table 'table_1':
    a1  a2
    1   2
    3   4

chartObject = ScatterPlot('table_1', ['a1', 'a2'])
chartObject.getJFreeChart().getPlot().setDomainAxis(BetterLogarithmicAxis('axis_name'))
chartObject.show()
    

                        table 'table':
                        a1  a2
                        1   2
                        3 4
chartObject = ScatterPlot('table', ['a1', 'a2'])
plot = chartObject.getJFreeChart().getPlot()
m = org.jfree.chart.plot.ValueMarker(2)
m.label = 'marker_label'
plot.addDomainMarker(m)
chartObject.show()