SVG::Graph::Bar

Create presentation quality SVG bar graphs easily

Synopsis

  require 'SVG/Graph/Bar'

  fields = %w(Jan Feb Mar);
  data_sales_02 = %w(12 45 21)

  graph = SVG::Graph::Bar.new({
    :height => 500,
    :width => 300,
    :fields => fields
  })

  graph.add_data({
    :data => data_sales_02,
    :title => 'Sales 2002'
  })

  print "Content-type: image/svg+xml\r\n\r\n"
  print graph.burn

Description

This object aims to allow you to easily create high quality SVG bar graphs. You can either use the default style sheet or supply your own. Either way there are many options which can be configured to give you control over how the graph is generated - with or without a key, data elements at each point, title, subtitle etc.

Notes

The default stylesheet handles upto 12 data sets, if you use more you must create your own stylesheet and add the additional settings for the extra data sets. You will know if you go over 12 data sets as they will have no style and be in black.

Examples

germane-software.com/repositories/public/SVG/test.rb

Acknowledgements

Leo Lapworth for creating the SVG::TT::Graph package which this Ruby port is based on.

Stephen Morgan for creating the TT template and SVG.

Author

Sean E. Russell <serATgermaneHYPHENsoftwareDOTcom>

Options

These options can be set in the config passed to the initializer, or they can be set via "=" methods after object instantiation.

height: Set the height of the graph box, this is the total height of the SVG box created - not the graph it self which auto scales to fix the space.
width: Set the width of the graph box, this is the total width of the SVG box created - not the graph it self which auto scales to fix the space.
style_sheet: Set the path to an external stylesheet, set to ’’ if you want to revert back to using the defaut internal version.
To create an external stylesheet create a graph using the default internal version and copy the stylesheet section to an external file and edit from there.
show_data_values: (Bool) Show the value of each element of data on the graph
bar_gap: Whether to have a gap between the bars or not, default is true, set to false if you don’t want gaps.
min_scale_value: The point at which the Y axis starts, defaults to ‘0’, if set to nil it will default to the minimum data value.
show_x_labels: Whether to show labels on the X axis or not, defaults to true, set to false if you want to turn them off.
stagger_x_labels: This puts the labels at alternative levels so if they are long field names they will not overlap so easily. Default it false, to turn on set to true.
rotate_x_labels: This turns the X axis labels by 90 degrees. Default it false, to turn on set to true.
show_y_labels: Whether to show labels on the Y axis or not, defaults to true, set to false if you want to turn them off.
scale_integers: Ensures only whole numbers are used as the scale divisions. Default it false, to turn on set to true. This has no effect if scale divisions are less than 1.
scale_divisions: This defines the gap between markers on the Y axis, default is a 10th of the max_value, e.g. you will have 10 markers on the Y axis. NOTE: do not set this too low - you are limited to 999 markers, after that the graph won’t generate.
show_x_title: Whether to show the title under the X axis labels, default is false, set to true to show.
x_title: What the title under X axis should be, e.g. ‘Months’.
show_y_title: Whether to show the title under the Y axis labels, default is false, set to true to show.
y_title_text_direction: Aligns writing mode for Y axis label. Defaults to :bt (Bottom to Top). Change to :tb (Top to Bottom) to reverse.
y_title: What the title under Y axis should be, e.g. ‘Sales in thousands’.
show_graph_title: Whether to show a title on the graph, defaults to false, set to true to show.
graph_title: What the title on the graph should be.
show_graph_subtitle: Whether to show a subtitle on the graph, defaults to false, set to true to show.
graph_subtitle: What the subtitle on the graph should be.
key: Whether to show a key, defaults to false, set to true if you want to show it.
key_position: Where the key should be positioned, defaults to :right, set to :bottom if you want to move it.
stack: How to stack data sets. :overlap overlaps bars with transparent colors, :top stacks bars on top of one another, :side stacks the bars side-by-side. Defaults to :overlap.

The constructor takes a hash reference, fields (the names for each field on the X axis) MUST be set, all other values are defaulted to those shown above - with the exception of style_sheet which defaults to using the internal style sheet.

   require 'SVG/Graph/Bar'

   # Field names along the X axis
   fields = %w(Jan Feb Mar)

   graph = SVG::Graph::Bar.new({
      # Required
      :fields => fields,

      # Optional - defaults shown
      :height            => 500,
      :width             => 300,
      :show_data_values  => true,

      :min_scale_value   => 0,
      :stagger_x_labels  => false,
      :rotate_x_labels   => false,
      :bar_gap           => true,

      :show_x_labels     => true,
      :show_y_labels     => true,
      :scale_integers    => false,
      :scale_divisions   => 0,

      :show_x_title      => false,
      :x_title           => 'X Field names',

      :show_y_title      => false,
      :y_title_text_direction => :bt,
      :y_title           => 'Y Scale',

      :show_graph_title  => false,
      :graph_title       => 'Graph Title',
      :show_graph_subtitle   => false,
      :graph_subtitle        => 'Graph Sub Title',

      :key                   => false,
      :key_position          => :right,

      # Optional - defaults to using internal stylesheet
      :style_sheet       => '/includes/graph.css'
   })

bar_gap	[RW]
graph_subtitle	[RW]
graph_title	[RW]
height	[RW]
key	[RW]
key_position	[RW]
min_scale_value	[RW]
rotate_x_labels	[RW]
scale_divisions	[RW]
scale_integers	[RW]
show_data_values	[RW]
show_graph_subtitle	[RW]
show_graph_title	[RW]
show_x_labels	[RW]
show_x_title	[RW]
show_y_labels	[RW]
show_y_title	[RW]
stack	[RW]
stagger_x_labels	[RW]
style_sheet	[RW]
width	[RW]
x_title	[RW]
y_title	[RW]
y_title_text_direction	[RW]