ChartDirector Ver 3.0 (Python Edition)

X Zone Colors




This example demonstates using x zone colors - colors that change at certain x value thresholds.

In this example, x zone colors are used as the color of the line, and as the fill color of the band the surrounds the line.

The x zone color for the line is configured to change from blue to a red dash line color upon reaching a certain x value threshold. The x zone color for the band is configured to change from semi-transparent blue to semi-transparent red upon reaching the same threshold.

X zone colors are created using Layer.xZoneColor. You can use a x zone color in any ChartDirector API that expects a color. For instance, you can use a x zone color as background color, fill color of data sets, line color, etc.

A single x zone color can support one threshold value and change between two colors. The two colors can be any colors, including another x zone colors. You may create x zone colors with multiple thresholds by cascading multiple x zone colors this way.

Source Code Listing

[File: pythondemo/xzonecolor.py] (The CGI version is available as "pythondemo_cgi/xzonecolor.py".)
#!/usr/bin/python from pychartdir import * #The data for the chart data = [50, 55, 47, 34, 42, 49, 63, 62, 73, 59, 56, 50, 64, 60, 67, 67, 58, 59, 73, 77, 84, 82, 80, 84, 89] #The error data representing the error band around the data points errData = [5, 6, 5.1, 6.5, 6.6, 8, 5.4, 5.1, 4.6, 5.0, 5.2, 6.0, 4.9, 5.6, 4.8, 6.2, 7.4, 7.1, 6.5, 9.6, 12.1, 15.3, 18.5, 20.9, 24.1] #The labels for the chart labels = ["Jan 01", "-", "-", "Apr", "-", "-", "Jul", "-", "-", "Oct", "-", "-", "Jan 02", "-", "-", "Apr", "-", "-", "Jul", "-", "-", "Oct", "-", "-", "Jan 03"] #Create a XYChart object of size 550 x 220 pixels c = XYChart(550, 220) #Set the plot area at (50, 5) and of size 480 x 180 pixels. Enabled both #vertical and horizontal grids by setting their colors to light grey (0xc0c0c0) c.setPlotArea(50, 5, 480, 180).setGridColor(0xc0c0c0, 0xc0c0c0) #Add a legend box (50, 5) (top of plot area) using horizontal layout. Use 8 pts #Arial font. Disable bounding box (set border to transparent). legendBox = c.addLegend(50, 5, 0, "", 8) legendBox.setBackground(Transparent) #Add keys to the legend box to explain the color zones legendBox.addKey("Historical", 0x9999ff) legendBox.addKey("Forecast", 0xff9966) #Add a title to the y axis. c.yAxis().setTitle("Energy Consumption") #Set the labels on the x axis c.xAxis().setLabels(labels) #Add a line layer to the chart layer = c.addLineLayer2() #Create the color to draw the data line. The line is blue (0x333399) to the left #of x = 18, and become a red (0xd04040) dash line to the right of x = 18. lineColor = layer.xZoneColor(18, 0x333399, c.dashLineColor(0xd04040, DashLine)) #Add the data line layer.addDataSet(data, lineColor) #Create the color to draw the err zone. The color is semi-transparent blue #(0x809999ff) to the left of x = 18, and become semi-transparent red #(0x80ff9966) to the right of x = 18. errColor = layer.xZoneColor(18, 0x809999ff, 0x80ff9966) #Add the upper border of the err zone layer.addDataSet(ArrayMath(data).add(errData).result(), errColor) #Add the lower border of the err zone layer.addDataSet(ArrayMath(data).sub(errData).result(), errColor) #Set the default line width to 2 pixels layer.setLineWidth(2) #Color the region between the err zone lines c.addInterLineLayer(layer.getLine(1), layer.getLine(2), errColor) #output the chart c.makeChart("xzonecolor.png")