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 43 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 @maximum_x_value = nil @minimum_x_value = nil end
# File lib/gruff/line.rb, line 212 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 end # there is at least one data point one_point = true end end return one_point end
This method allows one to plot a dataset with both X and Y data.
Parameters are as follows:
name: string, the title of the dataset x_data_points: an array containing the x data points for the graph y_data_points: an array containing the y data points for the graph color: hex number indicating the line color as an RGB triplet Notes: -if (x_data_points.length != y_data_points.length) an error is returned. -if the color argument is nil, the next color from the default theme will be used. -if you want to use a preset theme, you must set it before calling dataxy().
Example:
g = Gruff::Line.new g.title = "X/Y Dataset" g.dataxy("Apples", [1,3,4,5,6,10], [1, 2, 3, 4, 4, 3]) g.dataxy("Bapples", [1,3,4,5,7,9], [1, 1, 2, 2, 3, 3]) #you can still use the old data method too if you want: g.data("Capples", [1, 1, 2, 2, 3, 3]) #labels will be drawn at the x locations of the 1st dataset that you #passed in. In this example the lables are drawn at x locations 1,4,6 g.labels = {0 => '2003', 2 => '2004', 4 => '2005'} #labels
# File lib/gruff/line.rb, line 85 def dataxy(name, x_data_points=[], y_data_points=[], color=nil) raise ArgumentError, "x_data_points is nil!" if x_data_points.length == 0 if x_data_points.all?{|p| p.size == 2} x_data_points, y_data_points = x_data_points.map{|p| p[0]}, x_data_points.map{|p| p[1]} end raise ArgumentError, "x_data_points.length != y_data_points.length!" if x_data_points.length != y_data_points.length #call the existing data routine for the y data. self.data(name, y_data_points, color) x_data_points = Array(x_data_points) # make sure it's an array #append the x data to the last entry that was just added in the @data member lastElem = @data.length()-1 @data[lastElem][DATA_VALUES_X_INDEX] = x_data_points # Update the global min/max values for the x data x_data_points.each_with_index do |x_data_point, index| next if x_data_point.nil? # Setup max/min so spread starts at the low end of the data points if @maximum_x_value.nil? && @minimum_x_value.nil? @maximum_x_value = @minimum_x_value = x_data_point end @maximum_x_value = (x_data_point > @maximum_x_value) ? x_data_point : @maximum_x_value @minimum_x_value = (x_data_point < @minimum_x_value) ? x_data_point : @minimum_x_value end end
# File lib/gruff/line.rb, line 119 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 #normalize the x data if it is specified @data.each_with_index do |data_row, index| norm_x_data_points = [] if (data_row[DATA_VALUES_X_INDEX] != nil) data_row[DATA_VALUES_X_INDEX].each do |x_data_point| norm_x_data_points << ( (x_data_point.to_f - @minimum_x_value.to_f ) / (@maximum_x_value.to_f - @minimum_x_value.to_f) ) end @norm_data[index] << norm_x_data_points end end 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_with_index do |data_row, dr_index| 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| next if data_point.nil? x_data = data_row[DATA_VALUES_X_INDEX] if (x_data == nil) #use the old method: equally spaced points along the x-axis new_x = @graph_left + (@x_increment * index) else new_x = getXCoord(x_data[index], @graph_width, @graph_left) end 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
# File lib/gruff/line.rb, line 208 def getXCoord(x_data_point, width, offset) return(x_data_point * width + offset) end
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