JRuby + JFreeChart = Sparklines

Inspired by how easy it was to get JFreeChart working and some code from former colleague Andrew Bruno, I thought it’d be nice to write some JRuby to generate Edward Tufte’s Sparklines.

Here’s some simple example code on a semi-random dataset:

# Mostly inspired by
# http://left.subtree.org/2007/01/15/creating-sparklines-with-jfreechart/
# have JFreeChart in your classpath, obviously, as well as jcommon.jar
require 'java'

module Graph
  class Sparkline
    include_class 'java.io.File'
    include_class 'org.jfree.chart.ChartUtilities'
    include_class 'org.jfree.chart.JFreeChart'
    include_class 'org.jfree.chart.axis.NumberAxis'
    include_class 'org.jfree.chart.plot.XYPlot'
    include_class 'org.jfree.chart.renderer.xy.StandardXYItemRenderer'
    include_class 'org.jfree.data.xy.XYSeries'
    include_class 'org.jfree.data.xy.XYSeriesCollection'
    include_class 'org.jfree.chart.plot.PlotOrientation'

    def initialize(width=200, height=80, data=[])
      @width = width
      @height = height
      dataset = create_sample_data() if data.empty?
      @chart = create_chart(dataset)
    end

    def render_to_file(filename, format="png")
      javafile = java.io.File.new(filename)
      ChartUtilities.saveChartAsPNG(javafile, @chart, @width, @height)
    end

    private
    def create_sample_data
       series = XYSeries.new("Sparkline")
      data = [20]
      (1..99).each {|x|
        y = (data.last + (rand(x) + 1)) / 2
        data << y
        series.add(x, y)
      }

      dataset = XYSeriesCollection.new
      dataset.addSeries(series)
      return dataset
    end

    def create_chart(dataset)
      x = NumberAxis.new
      x.setTickLabelsVisible(false)
      x.setTickMarksVisible(false)
      x.setAxisLineVisible(false)
      x.setNegativeArrowVisible(false)
      x.setPositiveArrowVisible(false)
      x.setVisible(false)

      y = NumberAxis.new
      y.setTickLabelsVisible(false)
      y.setTickMarksVisible(false)
      y.setAxisLineVisible(false)
      y.setNegativeArrowVisible(false)
      y.setPositiveArrowVisible(false)
      y.setVisible(false)

      plot = XYPlot.new
      plot.setDataset(dataset)
      plot.setDomainAxis(x)
      plot.setDomainGridlinesVisible(false)
      plot.setDomainCrosshairVisible(false)
      plot.setRangeGridlinesVisible(false)
      plot.setRangeCrosshairVisible(false)
      plot.setRangeAxis(y)
      plot.setOutlinePaint(nil)
      plot.setRenderer(StandardXYItemRenderer.new(StandardXYItemRenderer::LINES))

      chart = JFreeChart.new(nil, JFreeChart::DEFAULT_TITLE_FONT, plot, false)
      chart.setBorderVisible(false);
      return chart
    end

  end # class Sparkline  
end # class Graph

sp = Graph::Sparkline.new
puts "Rendering sparkline"
sp.render_to_file("sparkline.png")

And the resulting sparkline chart:
An Example Sparkline Chart

Code: http://kfahlgren.com/code/sparkline.jrb

UPDATE: Removed some of the useless sample generation code

This entry was posted on Friday, April 13th, 2007 at 2:43 pm and is filed under Code, JRuby, Ruby. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

6 Responses to “JRuby + JFreeChart = Sparklines”

mdweezer says:

July 11, 2007 at 9:58 am

Have you done anything with DefaultCategoryDatasets? I’m trying to build some stacked bar charts in JRuby and your code is excellent but I can’t seem to make things work with other types of datasets, grrrrr. But then again, my Ruby isn’t exactly sharp.

The following chunk of code is what I need to port over…

DefaultCategoryDataset result = new DefaultCategoryDataset();
result.addValue(0, “Closed”, “”);
result.addValue(0, “InVerfication”, “”);
result.addValue(0, “Delivered”, “”);
result.addValue(0, “On-hold”, “”);
result.addValue(0, “In-work”, “”);
result.addValue(0, “Rejected”, “”);
result.addValue(0, “Duplicate”, “”);
result.addValue(0, “Assigned”, “”);
result.addValue(0, “Submitted”, “”);

Keith says:

July 11, 2007 at 2:40 pm

mdweezer:

I haven’t the foggiest idea what you’re actually trying to do, but:

# Mostly inspired by http://left.subtree.org/2007/01/15/creating-sparklines-with-jfreechart/
# have JFreeChart in your classpath, obviously, as well as jcommon.jar
require 'java'

module Graph
  class Sparkline
    include_class 'java.io.File'
    include_class 'org.jfree.chart.ChartUtilities'
    include_class 'org.jfree.chart.JFreeChart'
    include_class 'org.jfree.data.category.DefaultCategoryDataset'
    include_class 'org.jfree.chart.ChartFactory'
    include_class 'org.jfree.chart.plot.PlotOrientation'

    def initialize(width=200, height=80, data=[])
      @width = width
      @height = height
      dataset = create_sample_data() if data.empty?
      @chart = create_chart(dataset)
    end

    def render_to_file(filename, format="png")
      javafile = java.io.File.new(filename)
      ChartUtilities.saveChartAsPNG(javafile, @chart, @width, @height)
    end

    private
    def create_sample_data
      dataset = DefaultCategoryDataset.new
      dataset.addValue(1, "Closed", "")
      dataset.addValue(1, "InVerfication", "")
      dataset.addValue(2, "Delivered", "")
      dataset.addValue(2, "On-hold", "")
      dataset.addValue(3, "In-work", "")
      dataset.addValue(3, "Rejected", "")
      dataset.addValue(3, "Duplicate", "")
      dataset.addValue(3, "Assigned", "")
      dataset.addValue(4, "Submitted", "")

      return dataset
    end

    def create_chart(dataset)
      chart = ChartFactory.createWaterfallChart("Phase","Name", "", dataset, PlotOrientation::VERTICAL, true, true, false)
      return chart
    end
  end # class Sparkline
end # class Graph

sp = Graph::Sparkline.new
puts "Rendering sparkline"
sp.render_to_file("sparkline.png")

mdweezer says:

July 12, 2007 at 4:28 am

Keith,

I appreciate the response, I kept getting “addValue” incorrect method errors… I’m building stacked bar charts with the data. I’m using data scraped from a database, I just used those values to figure out how to actually add data to the dataset. Not quite sure what I was doing wrong but I”ll see what I can do. Again, I appreciate it, thanks!
Keith says:

July 12, 2007 at 6:23 am

What’s the actual error you’re getting/can you post more of the code you’re using?

Hope this helps
slonkak says:

April 17, 2008 at 10:40 am

Would you be so kind as to help our a Ruby/Java noob? Say I just created a default, blank rails app in my jRuby install. I have the jfreechart and jcommon JARs in my classpath. What all do I have to do to get your code to work and start producing charts. I don’t know Ruby (nor the MVC framework), I don’t know Java, and I most certainly don’t know how Java works with jRuby. I would like to learn, but since I learn by example, and most examples on the net are very incomplete, I’m having a hard time. Could you provide any assistance?
punk21 says:

June 17, 2008 at 8:22 pm

Hey guys, Having problem while drawing Sparkline Charts then chk this out visifire an amazing charting component which is powered by silverlight offered under open source