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 #, #, #, and #.
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
Disabled; run with --debug to generate this.
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