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.
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 def initialize(*args) raise ArgumentError, "Wrong number of arguments" if args.length > 2 if args.empty? or ((not Numeric === args.first) && (not String === args.first)) then super() else super args.shift end @hide_dots = @hide_lines = false @baseline_color = 'red' @baseline_value = nil end
# File lib/gruff/line.rb, line 118 def contains_one_point_only?(data_row) # Spin through data to determine if there is just one_value present. one_point = false data_row[DATA_VALUES_INDEX].each do |data_point| if !data_point.nil? if one_point # more than one point, bail return false else # there is at least one data point return true end end end return one_point end
# File lib/gruff/line.rb, line 52 def draw super return unless @has_data # Check to see if more than one datapoint was given. NaN can result otherwise. @x_increment = (@column_count > 1) ? (@graph_width / (@column_count - 1).to_f) : @graph_width if (defined?(@norm_baseline)) then level = @graph_top + (@graph_height - @norm_baseline * @graph_height) @d = @d.push @d.stroke_color @baseline_color @d.fill_opacity 0.0 @d.stroke_dasharray(10, 20) @d.stroke_width 5 @d.line(@graph_left, level, @graph_left + @graph_width, level) @d = @d.pop end @norm_data.each do |data_row| prev_x = prev_y = nil @one_point = contains_one_point_only?(data_row) data_row[DATA_VALUES_INDEX].each_with_index do |data_point, index| new_x = @graph_left + (@x_increment * index) next if data_point.nil? draw_label(new_x, index) new_y = @graph_top + (@graph_height - data_point * @graph_height) # Reset each time to avoid thin-line errors @d = @d.stroke data_row[DATA_COLOR_INDEX] @d = @d.fill data_row[DATA_COLOR_INDEX] @d = @d.stroke_opacity 1.0 @d = @d.stroke_width line_width || clip_value_if_greater_than(@columns / (@norm_data.first[DATA_VALUES_INDEX].size * 4), 5.0) circle_radius = dot_radius || clip_value_if_greater_than(@columns / (@norm_data.first[DATA_VALUES_INDEX].size * 2.5), 5.0) if !@hide_lines and !prev_x.nil? and !prev_y.nil? then @d = @d.line(prev_x, prev_y, new_x, new_y) elsif @one_point # Show a circle if there's just one_point @d = @d.circle(new_x, new_y, new_x - circle_radius, new_y) end @d = @d.circle(new_x, new_y, new_x - circle_radius, new_y) unless @hide_dots prev_x = new_x prev_y = new_y end end @d.draw(@base_image) end
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