Class Gruff::Line
In: lib/gruff/line.rb
Parent: Gruff::Base
StackedMixin StackedBar SideStackedBar StackedArea AccumulatorBar Base Scene Pie Area PhotoBar Bullet Spider SideBar Net Bar Dot Line Pie Observable Group SideBar StandardError IncorrectNumberOfDatasetsException Magick Bar Layer BarConversion lib/gruff/stacked_area.rb lib/gruff/scene.rb lib/gruff/spider.rb lib/gruff/pie.rb lib/gruff/bullet.rb lib/gruff/area.rb lib/gruff/net.rb lib/gruff/bar_conversion.rb lib/gruff/side_bar.rb lib/gruff/bar.rb lib/gruff/line.rb lib/gruff/stacked_bar.rb lib/gruff/dot.rb lib/gruff/side_stacked_bar.rb lib/gruff/photo_bar.rb lib/gruff/base.rb lib/gruff/accumulator_bar.rb lib/gruff/mini/bar.rb lib/gruff/mini/side_bar.rb lib/gruff/mini/pie.rb Legend Mini Deprecated Gruff dot/m_17_0.png

Here‘s how to make a Line graph:

  g = Gruff::Line.new
  g.title = "A Line Graph"
  g.data 'Fries', [20, 23, 19, 8]
  g.data 'Hamburgers', [50, 19, 99, 29]
  g.write("test/output/line.png")

There are also other options described below, such as baseline_value, baseline_color, hide_dots, and hide_lines.

Methods

Attributes

baseline_color  [RW]  Color of the baseline
baseline_value  [RW]  Draw a dashed line at the given value
dot_radius  [RW] 
hide_dots  [RW]  Hide parts of the graph to fit more datapoints, or for a different appearance.
hide_lines  [RW]  Hide parts of the graph to fit more datapoints, or for a different appearance.
line_width  [RW]  Dimensions of lines and dots; calculated based on dataset size if left unspecified

Public Class methods

Call with target pixel width of graph (800, 400, 300), and/or ‘false’ to omit lines (points only).

 g = Gruff::Line.new(400) # 400px wide with lines

 g = Gruff::Line.new(400, false) # 400px wide, no lines (for backwards compatibility)

 g = Gruff::Line.new(false) # Defaults to 800px wide, no lines (for backwards compatibility)

The preferred way is to call hide_dots or hide_lines instead.

[Source]

    # File lib/gruff/line.rb, line 39
39:   def initialize(*args)
40:     raise ArgumentError, "Wrong number of arguments" if args.length > 2
41:     if args.empty? or ((not Numeric === args.first) && (not String === args.first)) then
42:       super()
43:     else
44:       super args.shift
45:     end
46: 
47:     @hide_dots = @hide_lines = false
48:     @baseline_color = 'red'
49:     @baseline_value = nil
50:   end

Public Instance methods

[Source]

     # File lib/gruff/line.rb, line 118
118:   def contains_one_point_only?(data_row)
119:     # Spin through data to determine if there is just one_value present.
120:     one_point = false
121:     data_row[DATA_VALUES_INDEX].each do |data_point|
122:       if !data_point.nil?
123:         if one_point
124:           # more than one point, bail
125:           return false
126:         else
127:           # there is at least one data point
128:           return true
129:         end
130:       end
131:     end
132:     return one_point
133:   end

[Source]

     # File lib/gruff/line.rb, line 52
 52:   def draw
 53:     super
 54: 
 55:     return unless @has_data
 56: 
 57:     # Check to see if more than one datapoint was given. NaN can result otherwise.
 58:     @x_increment = (@column_count > 1) ? (@graph_width / (@column_count - 1).to_f) : @graph_width
 59: 
 60:     if (defined?(@norm_baseline)) then
 61:       level = @graph_top + (@graph_height - @norm_baseline * @graph_height)
 62:       @d = @d.push
 63:       @d.stroke_color @baseline_color
 64:       @d.fill_opacity 0.0
 65:       @d.stroke_dasharray(10, 20)
 66:       @d.stroke_width 5
 67:       @d.line(@graph_left, level, @graph_left + @graph_width, level)
 68:       @d = @d.pop
 69:     end
 70: 
 71:     @norm_data.each do |data_row|
 72:       prev_x = prev_y = nil
 73: 
 74:       @one_point = contains_one_point_only?(data_row)
 75: 
 76:       data_row[DATA_VALUES_INDEX].each_with_index do |data_point, index|
 77:         new_x = @graph_left + (@x_increment * index)
 78:         next if data_point.nil?
 79: 
 80:         draw_label(new_x, index)
 81: 
 82:         new_y = @graph_top + (@graph_height - data_point * @graph_height)
 83: 
 84:         # Reset each time to avoid thin-line errors
 85:         @d = @d.stroke data_row[DATA_COLOR_INDEX]
 86:         @d = @d.fill data_row[DATA_COLOR_INDEX]
 87:         @d = @d.stroke_opacity 1.0
 88:         @d = @d.stroke_width line_width ||
 89:           clip_value_if_greater_than(@columns / (@norm_data.first[DATA_VALUES_INDEX].size * 4), 5.0)
 90: 
 91: 
 92:         circle_radius = dot_radius ||
 93:           clip_value_if_greater_than(@columns / (@norm_data.first[DATA_VALUES_INDEX].size * 2.5), 5.0)
 94: 
 95:         if !@hide_lines and !prev_x.nil? and !prev_y.nil? then
 96:           @d = @d.line(prev_x, prev_y, new_x, new_y)
 97:         elsif @one_point
 98:           # Show a circle if there's just one_point
 99:           @d = @d.circle(new_x, new_y, new_x - circle_radius, new_y)
100:         end
101:         @d = @d.circle(new_x, new_y, new_x - circle_radius, new_y) unless @hide_dots
102: 
103:         prev_x = new_x
104:         prev_y = new_y
105:       end
106: 
107:     end
108: 
109:     @d.draw(@base_image)
110:   end

[Source]

     # File lib/gruff/line.rb, line 112
112:   def normalize
113:     @maximum_value = [@maximum_value.to_f, @baseline_value.to_f].max
114:     super
115:     @norm_baseline = (@baseline_value.to_f / @maximum_value.to_f) if @baseline_value
116:   end

[Validate]