Prawn::Graph - Easy Graphing for Prawn

An extension for the prawn pdf library which adds the ability to draw graphs (or charts if you perfer) in PDF documents.

Because Prawn::Graph only uses the native PDF drawing functions exposed by Prawn, it removes the need to depend on projects like Gruff to generate heavy PNG / JPG images of such graphs and charts and then include those large blobs in your documents. The results may not be as pretty (yet), but the file-size differences are dramatic.

By default, graphs are drawn in monochrome, as that's likely how they will be printed.

This is free and open source software released under ther terms of the MIT Licence.

Its copyright is held by Ryan Stenhouse and the other contributors and it was first released in 2010.

Compatibility

This gem is built assuming a Ruby version of 2.0 or higher. Older Ruby versions may work but are not officially supported. We aim for compatibilty with 1.x and 2.x series of prawn. Any incomaptibilities with prawn versions should be treated as bugs and added to the issue tracker.

We build automatically using Travis CI. Our .travis.yml file targets the same Ruby versions as prawn itself does.

Removed features:

Unlike previous versions of prawn-graph, this version does not at this time include a theme api or the ability to change the colors used to render the graph.

Removed deprecated methods

The bar_chart, line_chart, bar_graph, and line_graph methods have been removed. This means that this version of prawn-graph is no-longer backwards compatible. If you must use those old methods, then please use version 0.9.10 and upgrade your calls to prawn graph to use the new graph methods as soon as possible.

Installation

To use prawn-graph, you can add the following to your Gemfile:

 gem 'prawn-graph', ' ~> 1.0'

Alternatively, you can use Rubygems directly: gem install prawn-graph.

Acknowledgements

With thanks to 株式会社アルム (Allm Inc) for allowing Ryan Stenhouse the time to rebuild this version of prawn-graph. This updated version of prawn-graph was inspired and guided by prawn-svg by Roger Nesbitt.

Prawn Graph was originally sponsored by and built for use at Purchasing Card Consultancy Ltd while Ryan Stenhouse was employed there.

Supported graph / chart types

This version of Prawn::Graph supports the following graph / chart types:

Bar Charts
Line Charts

Is your favourite chart type not supported yet? Please request it, or if you are feeling particularly adventurous - please add it!

Using prawn-graph

Graphs can be created by calling the graph or its alias, chart method with an array of Prawn::Graph::Series objects representing the data you would like to plot and how it should be displayed. It will also take a hash of options, and block which will have the graph yeilded to it.

  graph data, options = {}, &block.

When called with just a set of data, prawn-graph will do its best to make the graph fit in the available space. For a little more control over how the graphs are rendered in the document you can pass the following options to graph or chart:

Option	Data type	Description
:at	[integer, integer]	Specify the location on the page you want the graph to appear.
:width	integer	Desired width of the graph. Defaults to horizontal space available.
:height	integer	Desired height of the graph. Defaults to vertical space available.
:title	string	The overall title for your chart
:series_key	boolean	Should we render the series key for multi series graphs? Defaults to true.
:theme	Prawn::Graph::Theme	An instance of the Theme object which should be used to style this chart. Default is a greyscale theme for printing.

The data passed to graph or chart should be an Array of Prawn::Graph::Series objects, which themselves are made up of an array of data points to plot, and a series of options.

  Prawn::Graph::Series.new [1,2,3,4], options = {}

Valid options are:

Option	Data type	Description
:mark_average	boolean	Should we mark a line showing the average value of the series? Defaults to false.
:mark_minimum	boolean	Should we mark the minimum value of the series? Defaults to false.
:mark_maximum	boolean	Should we mark the maximum value of the series? Defaults to false.
:title	string	The title of this series, which will be shown in the series key.
:type	symbol	How this series should be rendered. Defaults to `:bar`, valid options are `:bar`, `:line`.

Show me some code!

  require 'prawn-graph'

  series = []
  series << Prawn::Graph::Series.new([4,9,3,2,1,6,2,8,2,3,4,9,2],  title: "A label for a series", type: :bar)
  series << Prawn::Graph::Series.new([5,4,3,2,7,9,2,8,7,5,4,9,2],  title: "Another label", type: :line, mark_average: true, mark_minimum: true)
  series << Prawn::Graph::Series.new([1,2,3,4,5,9,6,4,5,6,3,2,11], title: "Yet another label", type: :bar)
  series << Prawn::Graph::Series.new([1,2,3,4,5,12,6,4,5,6,3,2,9].shuffle, title: "One final label", type: :line, mark_average: true, mark_maximum: true)

  xaxis_labels = ['0900', '1000', '1100', '1200', '1300', '1400', '1500', '1600', '1700', '1800', '1900', '2000', '2100']

  Prawn::Document.generate('test.pdf') do
    graph series, width: 500, height: 200, title: "A Title for the chart", at: [10,700], xaxis_labels: xaxis_labels
  end

Theming

You can pass an instnace of Prawn::Graph::Theme using the :theme option to the graph and chart methods. The theme expects to be initialised with a Hash in the following format:

{
  series:
    [
      'EBEDEF',
      'D6DBDF', 
      '85929E', 
      '34495E', 
      '1B2631' 
    ], 
  title:'17202A', 
  background:'FFFFFF', 
  grid:'F2F4F4', 
  axes:'17202A', 
  markers:'34495E', 
  stroke_grid_lines:true, 
  default:'333333', 
  average:'34495E', 
  max:'17202A',
  min:'17202A' 
}

Valid keys are:

Option	Data type	Description
:series	Array of Strings	HEX code colours used to draw a series on the chart. Will cycle through these are too many series for colors
:title	string	HEX color code used to color this part of the chart
:background	string	HEX color code used to color this part of the chart
:grid	string	HEX color code used to color this part of the chart
:axes	string	HEX color code used to color this part of the chart
:markers	string	HEX color code used to color this part of the chart
:stroke_grid_lines	boolean	Should the grid lines be stroked?
:default	string	HEX color code used to color this part of the chart
:average	string	HEX color code used to color this part of the chart
:max	string	HEX color code used to color this part of the chart
:min	string	HEX color code used to color this part of the chart

Output

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

rogsmith/prawn-graph