| Class | Gruff::Line |
| In: |
lib/gruff/line.rb
|
| Parent: | Gruff::Base |
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.
| 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 |
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.
# 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
# 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
# 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