ChartDirector Ver 4.1 (Python Edition)

Pareto Chart




This example demonstrates the pareto chart style.

A pareto chart is a bar chart with the data sorted in descending order, together with a line chart showing the same data in accumulated form. In the current example, the data is shown as both percentages and values on the two y-axes.

The chart in this example is composed of two layers - a BarLayer created using XYChart.addBarLayer, and a LineLayer created using XYChart.addLineLayer.

This example employs the ArrayMath utility class for computing the accumulated line, obtaining the scaling factor between the two y-axes, and re-scaling the line data as percentages.

The two y-axes are synchronized using XYChart.syncYAxis.

Source Code Listing

[Standalone Version] pythondemo\pareto.py
#!/usr/bin/python
from pychartdir import *

# The data for the chart
data = [40, 15, 7, 5, 2]

# The labels for the chart
labels = ["Hard Disk", "PCB", "Printer", "CDROM", "Keyboard"]

# Create a XYChart object of size 400 x 225 pixels. Use golden background color, with
# a 2 pixel 3D border.
c = XYChart(400, 225, goldColor(), -1, 2)

# Add a title box using Arial Bold/11 pt font. Set the background color to metallic
# blue (9999FF). Use a 1 pixel 3D border.
c.addTitle("Hardware Defects", "arialbd.ttf", 11).setBackground(metalColor(0x9999ff),
    -1, 1)

# Set the plotarea at (50, 40) and of 300 x 150 pixels in size, with a silver
# background color.
c.setPlotArea(50, 40, 300, 150, silverColor())

# Add a line layer for the pareto line
lineLayer = c.addLineLayer()

# Compute the pareto line by accumulating the data
lineData = ArrayMath(data)
lineData.acc()

# Set a scaling factor such as the maximum point of the line is scaled to 100
scaleFactor = 100 / lineData.max()

# Add the pareto line using the scaled data. Use deep blue (0x80) as the line color,
# with light blue (0x9999ff) diamond symbols
lineLayer.addDataSet(lineData.mul2(scaleFactor).result(), 0x000080).setDataSymbol(
    DiamondSymbol, 9, 0x9999ff)

# Set the line width to 2 pixel
lineLayer.setLineWidth(2)

# Add a multi-color bar layer using the given data.
barLayer = c.addBarLayer3(data)

# Bind the layer to the secondary (right) y-axis.
barLayer.setUseYAxis2()

# Set soft lighting for the bars with light direction from the right
barLayer.setBorderColor(Transparent, softLighting(Right))

# Set the labels on the x axis.
c.xAxis().setLabels(labels)

# Set the primary y-axis scale as 0 - 100 with a tick every 20 units
c.yAxis().setLinearScale(0, 100, 20)

# Set the label format of the y-axis label to include a percentage sign
c.yAxis().setLabelFormat("{value}%")

# Add a title to the secondary y-axis
c.yAxis2().setTitle("Frequency")

# Set the secondary y-axis label foramt to show no decimal point
c.yAxis2().setLabelFormat("{value|0}")

# Set the relationship between the two y-axes, which only differ by a scaling factor
c.syncYAxis(1 / scaleFactor)

# Output the chart
c.makeChart("pareto.png")

[CGI Version] pythondemo_cgi\pareto.py
#!/usr/bin/python
from pychartdir import *

# The data for the chart
data = [40, 15, 7, 5, 2]

# The labels for the chart
labels = ["Hard Disk", "PCB", "Printer", "CDROM", "Keyboard"]

# Create a XYChart object of size 400 x 225 pixels. Use golden background color, with
# a 2 pixel 3D border.
c = XYChart(400, 225, goldColor(), -1, 2)

# Add a title box using Arial Bold/11 pt font. Set the background color to metallic
# blue (9999FF). Use a 1 pixel 3D border.
c.addTitle("Hardware Defects", "arialbd.ttf", 11).setBackground(metalColor(0x9999ff),
    -1, 1)

# Set the plotarea at (50, 40) and of 300 x 150 pixels in size, with a silver
# background color.
c.setPlotArea(50, 40, 300, 150, silverColor())

# Add a line layer for the pareto line
lineLayer = c.addLineLayer()

# Compute the pareto line by accumulating the data
lineData = ArrayMath(data)
lineData.acc()

# Set a scaling factor such as the maximum point of the line is scaled to 100
scaleFactor = 100 / lineData.max()

# Add the pareto line using the scaled data. Use deep blue (0x80) as the line color,
# with light blue (0x9999ff) diamond symbols
lineLayer.addDataSet(lineData.mul2(scaleFactor).result(), 0x000080).setDataSymbol(
    DiamondSymbol, 9, 0x9999ff)

# Set the line width to 2 pixel
lineLayer.setLineWidth(2)

# Add a multi-color bar layer using the given data.
barLayer = c.addBarLayer3(data)

# Bind the layer to the secondary (right) y-axis.
barLayer.setUseYAxis2()

# Set soft lighting for the bars with light direction from the right
barLayer.setBorderColor(Transparent, softLighting(Right))

# Set the labels on the x axis.
c.xAxis().setLabels(labels)

# Set the primary y-axis scale as 0 - 100 with a tick every 20 units
c.yAxis().setLinearScale(0, 100, 20)

# Set the label format of the y-axis label to include a percentage sign
c.yAxis().setLabelFormat("{value}%")

# Add a title to the secondary y-axis
c.yAxis2().setTitle("Frequency")

# Set the secondary y-axis label foramt to show no decimal point
c.yAxis2().setLabelFormat("{value|0}")

# Set the relationship between the two y-axes, which only differ by a scaling factor
c.syncYAxis(1 / scaleFactor)

# Output the chart
print "Content-type: image/png\n"
binaryPrint(c.makeChart2(PNG))