ChartDirector Ver 3.0 (Python Edition)

Enhanced Line Chart




This example extends the Simple Line Chart example by decorating the chart using a number of chart formatting features.

In this example, random data is used. They are generated using a ChartDirector utility class RanTable. RanTable simulates a database table with the cells filled with random numbers. The columns of the table can be retrieved as arrays using RanTable.getCol.

Source Code Listing

[File: pythondemo/enhancedline.py] (The CGI version is available as "pythondemo_cgi/enhancedline.py".)
#!/usr/bin/python from pychartdir import * # # We use a random number generator to simulate the data from 9:30 to 4:30 # with one data point every 4 minutes. The total number of points during that # period is 106. (7 hours x 15 points/hour + 1) # noOfPoints = 106 #Assume we have not reached the end of the day yet, and only 85 points are #available. Create a random table object of 1 col x 85 rows, using 9 as seed. rantable = RanTable(9, 1, 85) #Set the 1st column to start with 1800 and with random delta from -5 to 5. rantable.setCol(0, 1800, -5, 5) #Get the data as the 1st column of the random table data = rantable.getCol(0) #The x-axis labels for the chart labels = ["-", "10am", "-", " ", "-", "12am", "-", " ", "-", "2pm", "-", " ", "-", "4pm", "-"] # # Now we obtain the data into arrays, we can start to draw the chart using # ChartDirector # #Create a XYChart object of size 180 x 180 pixels with a blue background #(0x9c9cce) c = XYChart(180, 180, 0x9c9cce) #Add titles to the top and bottom of the chart using 7.5pt Arial font. The text #is white 0xffffff on a deep blue 0x31319C background. c.addTitle2(Top, "STAR TECH INDEX 2003-01-28", "arial.ttf", 7.5, 0xffffff, 0x31319c) c.addTitle2(Bottom, "LATEST STI:1809.41 (+14.51)", "arial.ttf", 7.5, 0xffffff, 0x31319c) #Set the plotarea at (31, 21) and of size 145 x 124 pixels, with a pale yellow #(0xffffc8) background. c.setPlotArea(31, 21, 145, 124, 0xffffc8) #Add custom text at (176, 21) (top right corner of plotarea) using 11pt Times #Bold Italic font/red (0xc09090) color c.addText(176, 21, "Chart Demo", "timesbi.ttf", 11, 0xc09090).setAlignment( TopRight) #Use 7.5 pts Arial as the y axis label font c.yAxis().setLabelStyle("", 7.5) #Set the labels on the x axis by spreading the labels evenly between the first #point (index = 0) and the last point (index = noOfPoints - 1) c.xAxis().setLinearScale(0, noOfPoints - 1, labels) #Use 7.5 pts Arial as the x axis label font c.xAxis().setLabelStyle("", 7.5) #Add a deep blue (0x000080) line layer to the chart c.addLineLayer(data, 0x80) #output the chart c.makeChart("enhancedline.png")