ChartDirector 6.0 (Ruby Edition)

Missing Data Points




This example demonstrates various methods to representing missing data points. It also demonstrates automatic resizing of the plot area to fit the chart.

In ChartDirector, a data series may contain missing values, represented using the NoValue predefined constant. In a line layer, by default, a missing value is represented as a gap in the line. In other words, the line will be broken. LineLayer.setGapColor can be used to configure the line layer to join through the NoValue point instead, using a line segment that can be of a different color and/or style.

In this example, the three data series all contain NoValue points. The red line demonstrates the default behaviour of using a gap to representing the NoValue point. The green line demonstrates joining through the NoValue point with a dash line. The orange line demonstrates joining through the NoValue point with the same line style as for joining normal data points.

After the entire chart is configured, the XYChart.packPlotArea method is used to adjust the plot area size, so as to fit the plot area and the axes in a given bounding box.

Source Code Listing

[Ruby On Rails Version - Controller] app/controllers/missingpoints_controller.rb
require("chartdirector")

class MissingpointsController < ApplicationController

    def index()
        @title = "Missing Data Points"
        @ctrl_file = File.expand_path(__FILE__)
        @noOfCharts = 1
        render :template => "templates/chartview"
    end

    #
    # Render and deliver the chart
    #
    def getchart()
        # The data for the chart
        data0 = [42, 49, ChartDirector::NoValue, 38, 64, 56, 29, 41, 44, 57]
        data1 = [65, 75, 47, 34, 42, 49, 73, ChartDirector::NoValue, 90, 69, 66, 78]
        data2 = [ChartDirector::NoValue, ChartDirector::NoValue, 25, 28, 38, 20, 22,
            ChartDirector::NoValue, 25, 33, 30, 24]
        labels = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
            ]

        # Create a XYChart object of size 600 x 360 pixels. Set background color to brushed silver,
        # with a 2 pixel 3D border. Use rounded corners.
        c = ChartDirector::XYChart.new(600, 360, ChartDirector::brushedSilverColor(),
            ChartDirector::Transparent, 2)
        c.setRoundedFrame()

        # Add a title using 18pt Times New Roman Bold Italic font. #Set top/bottom margins to 6
        # pixels.
        title = c.addTitle("Product Line Global Revenue", "timesbi.ttf", 18)
        title.setMargin2(0, 0, 6, 6)

        # Add a separator line just under the title
        c.addLine(10, title.getHeight(), c.getWidth() - 11, title.getHeight(),
            ChartDirector::LineColor)

        # Add a legend box where the top-center is anchored to the horizontal center of the chart,
        # just under the title. Use horizontal layout and 10 points Arial Bold font, and transparent
        # background and border.
        legendBox = c.addLegend(c.getWidth() / 2, title.getHeight(), false, "arialbd.ttf", 10)
        legendBox.setAlignment(ChartDirector::TopCenter)
        legendBox.setBackground(ChartDirector::Transparent, ChartDirector::Transparent)

        # Tentatively set the plotarea at (70, 75) and of 460 x 240 pixels in size. Use transparent
        # border and black (000000) grid lines
        c.setPlotArea(70, 75, 460, 240, -1, -1, ChartDirector::Transparent, 0x000000, -1)

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

        # Show the same scale on the left and right y-axes
        c.syncYAxis()

        # Set y-axis tick density to 30 pixels. ChartDirector auto-scaling will use this as the
        # guideline when putting ticks on the y-axis.
        c.yAxis().setTickDensity(30)

        # Set all axes to transparent
        c.xAxis().setColors(ChartDirector::Transparent)
        c.yAxis().setColors(ChartDirector::Transparent)
        c.yAxis2().setColors(ChartDirector::Transparent)

        # Set the x-axis margins to 15 pixels, so that the horizontal grid lines can extend beyond
        # the leftmost and rightmost vertical grid lines
        c.xAxis().setMargin(15, 15)

        # Set axis label style to 8pt Arial Bold
        c.xAxis().setLabelStyle("arialbd.ttf", 8)
        c.yAxis().setLabelStyle("arialbd.ttf", 8)
        c.yAxis2().setLabelStyle("arialbd.ttf", 8)

        # Add axis title using 10pt Arial Bold Italic font
        c.yAxis().setTitle("Revenue in USD millions", "arialbi.ttf", 10)
        c.yAxis2().setTitle("Revenue in USD millions", "arialbi.ttf", 10)

        # Add the first line. The missing data will be represented as gaps in the line (the default
        # behaviour)
        layer0 = c.addLineLayer2()
        layer0.addDataSet(data0, 0xff0000, "Quantum Computer").setDataSymbol(
            ChartDirector::GlassSphere2Shape, 11)
        layer0.setLineWidth(3)

        # Add the second line. The missing data will be represented by using dash lines to bridge
        # the gap
        layer1 = c.addLineLayer2()
        layer1.addDataSet(data1, 0x00ff00, "Atom Synthesizer").setDataSymbol(
            ChartDirector::GlassSphere2Shape, 11)
        layer1.setLineWidth(3)
        layer1.setGapColor(c.dashLineColor(0x00ff00))

        # Add the third line. The missing data will be ignored - just join the gap with the original
        # line style.
        layer2 = c.addLineLayer2()
        layer2.addDataSet(data2, 0xff6600, "Proton Cannon").setDataSymbol(
            ChartDirector::GlassSphere2Shape, 11)
        layer2.setLineWidth(3)
        layer2.setGapColor(ChartDirector::SameAsMainColor)

        # layout the legend so we can get the height of the legend box
        c.layoutLegend()

        # Adjust the plot area size, such that the bounding box (inclusive of axes) is 15 pixels
        # from the left edge, just under the legend box, 16 pixels from the right edge, and 25
        # pixels from the bottom edge.
        c.packPlotArea(15, legendBox.getTopY() + legendBox.getHeight(), c.getWidth() - 16,
            c.getHeight() - 25)

        # Output the chart
        send_data(c.makeChart2(ChartDirector::JPG), :type => "image/jpeg", :disposition => "inline")

    end

end

[Ruby On Rails Version - View] app/views/templates/chartview.html.erb
<html>
<body style="margin:5px 0px 0px 5px">

<!-- Title -->
<div style="font-size:18pt; font-family:verdana; font-weight:bold">
    <%= @title %>
</div>
<hr style="border:solid 1px #000080" />

<!-- Source Code Listing Link -->
<div style="font-size:9pt; font-family:verdana; margin-bottom:1.5em">
    <%= link_to "Source Code Listing", 
        :controller => "cddemo", :action => "viewsource",
        :ctrl_file => @ctrl_file, :view_file => File.expand_path(__FILE__) %>
</div>

<!-- Create one or more IMG tags to display the demo chart(s) -->
<% 0.upto(@noOfCharts - 1) do |i| %>
    <img src="<%= url_for(:action => "getchart", :img => i) %>">
<% end %>

</body>
</html>

[Command Line Version] rubydemo/missingpoints.rb
#!/usr/bin/env ruby
require("chartdirector")

# The data for the chart
data0 = [42, 49, ChartDirector::NoValue, 38, 64, 56, 29, 41, 44, 57]
data1 = [65, 75, 47, 34, 42, 49, 73, ChartDirector::NoValue, 90, 69, 66, 78]
data2 = [ChartDirector::NoValue, ChartDirector::NoValue, 25, 28, 38, 20, 22, ChartDirector::NoValue,
    25, 33, 30, 24]
labels = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"]

# Create a XYChart object of size 600 x 360 pixels. Set background color to brushed silver, with a 2
# pixel 3D border. Use rounded corners.
c = ChartDirector::XYChart.new(600, 360, ChartDirector::brushedSilverColor(),
    ChartDirector::Transparent, 2)
c.setRoundedFrame()

# Add a title using 18pt Times New Roman Bold Italic font. #Set top/bottom margins to 6 pixels.
title = c.addTitle("Product Line Global Revenue", "timesbi.ttf", 18)
title.setMargin2(0, 0, 6, 6)

# Add a separator line just under the title
c.addLine(10, title.getHeight(), c.getWidth() - 11, title.getHeight(), ChartDirector::LineColor)

# Add a legend box where the top-center is anchored to the horizontal center of the chart, just
# under the title. Use horizontal layout and 10 points Arial Bold font, and transparent background
# and border.
legendBox = c.addLegend(c.getWidth() / 2, title.getHeight(), false, "arialbd.ttf", 10)
legendBox.setAlignment(ChartDirector::TopCenter)
legendBox.setBackground(ChartDirector::Transparent, ChartDirector::Transparent)

# Tentatively set the plotarea at (70, 75) and of 460 x 240 pixels in size. Use transparent border
# and black (000000) grid lines
c.setPlotArea(70, 75, 460, 240, -1, -1, ChartDirector::Transparent, 0x000000, -1)

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

# Show the same scale on the left and right y-axes
c.syncYAxis()

# Set y-axis tick density to 30 pixels. ChartDirector auto-scaling will use this as the guideline
# when putting ticks on the y-axis.
c.yAxis().setTickDensity(30)

# Set all axes to transparent
c.xAxis().setColors(ChartDirector::Transparent)
c.yAxis().setColors(ChartDirector::Transparent)
c.yAxis2().setColors(ChartDirector::Transparent)

# Set the x-axis margins to 15 pixels, so that the horizontal grid lines can extend beyond the
# leftmost and rightmost vertical grid lines
c.xAxis().setMargin(15, 15)

# Set axis label style to 8pt Arial Bold
c.xAxis().setLabelStyle("arialbd.ttf", 8)
c.yAxis().setLabelStyle("arialbd.ttf", 8)
c.yAxis2().setLabelStyle("arialbd.ttf", 8)

# Add axis title using 10pt Arial Bold Italic font
c.yAxis().setTitle("Revenue in USD millions", "arialbi.ttf", 10)
c.yAxis2().setTitle("Revenue in USD millions", "arialbi.ttf", 10)

# Add the first line. The missing data will be represented as gaps in the line (the default
# behaviour)
layer0 = c.addLineLayer2()
layer0.addDataSet(data0, 0xff0000, "Quantum Computer").setDataSymbol(
    ChartDirector::GlassSphere2Shape, 11)
layer0.setLineWidth(3)

# Add the second line. The missing data will be represented by using dash lines to bridge the gap
layer1 = c.addLineLayer2()
layer1.addDataSet(data1, 0x00ff00, "Atom Synthesizer").setDataSymbol(
    ChartDirector::GlassSphere2Shape, 11)
layer1.setLineWidth(3)
layer1.setGapColor(c.dashLineColor(0x00ff00))

# Add the third line. The missing data will be ignored - just join the gap with the original line
# style.
layer2 = c.addLineLayer2()
layer2.addDataSet(data2, 0xff6600, "Proton Cannon").setDataSymbol(ChartDirector::GlassSphere2Shape,
    11)
layer2.setLineWidth(3)
layer2.setGapColor(ChartDirector::SameAsMainColor)

# layout the legend so we can get the height of the legend box
c.layoutLegend()

# Adjust the plot area size, such that the bounding box (inclusive of axes) is 15 pixels from the
# left edge, just under the legend box, 16 pixels from the right edge, and 25 pixels from the bottom
# edge.
c.packPlotArea(15, legendBox.getTopY() + legendBox.getHeight(), c.getWidth() - 16, c.getHeight(
    ) - 25)

# Output the chart
c.makeChart("missingpoints.jpg")