ChartDirector Ver 3.0 (Python Edition)

Polar Bubble Chart




A polar bubble chart can be created as a polar line chart with circles as data symbols. The line width is set to 0, so only the symbols can be seen. The symbol sizes are then controlled using another data series. This will create the effects of a bubble chart.

The detail steps are:

Source Code Listing

[File: pythondemo/polarbubble.py] (The CGI version is available as "pythondemo_cgi/polarbubble.py".)
#!/usr/bin/python from pychartdir import * #The data for the chart data0 = [6, 12.5, 18.2, 15] angles0 = [45, 96, 169, 258] size0 = [41, 105, 12, 20] data1 = [18, 16, 11, 14] angles1 = [30, 210, 240, 310] size1 = [30, 45, 12, 90] #Create a PolarChart object of size 460 x 460 pixels c = PolarChart(460, 460) #Add a title to the chart at the top left corner using 15pts Arial Bold Italic #font c.addTitle2(TopLeft, "<*underline=2*>EM Field Strength", "arialbi.ttf", 15) #Set center of plot area at (230, 240) with radius 180 pixels c.setPlotArea(230, 240, 180) #Set the grid style to circular grid c.setGridStyle(0) #Add a legend box at the top right corner of the chart using 9 pts Arial Bold #font c.addLegend(459, 0, 1, "arialbd.ttf", 9).setAlignment(TopRight) #Set angular axis as 0 - 360, either spoke every 30 units c.angularAxis().setLinearScale(0, 360, 30) #Set the radial axis label format c.radialAxis().setLabelFormat("{value} km") #Add a blue (0x9999ff) line layer to the chart using (data0, angle0) layer0 = c.addLineLayer(data0, 0x9999ff, "Cold Spot") layer0.setAngles(angles0) #Disable the line by setting its width to 0, so only the symbols are visible layer0.setLineWidth(0) #Use a circular data point symbol layer0.setDataSymbol(CircleSymbol, 11) #Modulate the symbol size by size0 to produce a bubble chart effect layer0.setSymbolScale(size0) #Add a red (0xff9999) line layer to the chart using (data1, angle1) layer1 = c.addLineLayer(data1, 0xff9999, "Hot Spot") layer1.setAngles(angles1) #Disable the line by setting its width to 0, so only the symbols are visible layer1.setLineWidth(0) #Use a circular data point symbol layer1.setDataSymbol(CircleSymbol, 11) #Modulate the symbol size by size1 to produce a bubble chart effect layer1.setSymbolScale(size1) #output the chart c.makeChart("polarbubble.png")