Implements to display ytick

lib/rubyplot/artist/axes.rb

@@ -47,8 +47,12 @@ class Axes < Base
       attr_reader :y_axis
       # Array of X ticks.
       attr_reader :x_ticks
+      # Array of Y ticks.
+      attr_reader :y_ticks
       # Number of X ticks.
       attr_accessor :num_x_ticks
+      # Number of Y ticks.
+      attr_accessor :num_y_ticks
 
       # @param figure [Rubyplot::Figure] Figure object to which this Axes belongs.
       def initialize figure
@@ -89,7 +93,9 @@ def initialize figure
         @x_axis = Rubyplot::Artist::XAxis.new(self)
         @y_axis = Rubyplot::Artist::YAxis.new(self)
         @x_ticks = nil
+        @y_ticks = nil
         @num_x_ticks = 5
+        @num_y_ticks = 4
 
         @legend_box_position = :top
       end
@@ -125,6 +131,7 @@ def draw
         configure_title
         configure_legends
         assign_x_ticks
+        assign_y_ticks
         actually_draw
       end
 
@@ -197,6 +204,10 @@ def x_ticks= x_ticks
         @x_ticks = x_ticks
       end
 
+      def y_ticks= y_ticks
+        @y_ticks = y_ticks
+      end
+
       def x_title= x_title
         @x_axis.title = x_title
       end
@@ -236,6 +247,26 @@ def assign_x_ticks
         end
       end
 
+      def assign_y_ticks
+        unless @y_ticks
+          val_distance = (@y_range[1] - @y_range[0]).abs / @num_y_ticks.to_f
+          @y_ticks = (@y_range[0]..@y_range[1]).step(val_distance).map { |i| i }
+        end
+        unless @y_ticks.all? { |t| t.is_a?(Rubyplot::Artist::YTick) }
+          inter_ticks_distance = @y_axis.length / (@num_y_ticks - 1)
+          @y_ticks.map!.with_index do |tick_label, i|
+            Rubyplot::Artist::YTick.new(
+              self,
+              abs_x: @origin[0] - @x_axis_margin,
+              abs_y: @y_axis.abs_y1 - (i * inter_ticks_distance),
+              label: Rubyplot::Utils.format_label(tick_label),
+              length: 6,
+              label_distance: 10
+            )
+          end
+        end
+      end
+
       def add_plot plot_type, *args, &block
         plot = with_backend plot_type, *args
         yield(plot) if block_given?
@@ -291,6 +322,7 @@ def normalize_plotting_data
       def actually_draw
         @x_axis.draw
         @x_ticks.each(&:draw)
+        @y_ticks.each(&:draw)
         @y_axis.draw
         @title.draw
         @legend_box.draw

lib/rubyplot/artist/tick/y_tick.rb

@@ -1,6 +1,24 @@
 module Rubyplot
   module Artist
     class YTick < Tick::Base
+      def initialize(*)
+        super
+        @label = Rubyplot::Artist::Text.new(
+          @label_text.to_s,
+          @owner,
+          abs_x: @abs_x - 5,
+          abs_y: @abs_y + @length + @label_distance,
+          pointsize: @owner.marker_font_size,
+        )
+      end
+
+      def draw
+        @backend.draw_line(
+          x1: @abs_x, y1: @abs_y, x2: @abs_x, y2: @abs_y + @length,
+          stroke_opacity: @tick_opacity,
+          stroke_width: @tick_width)
+        @label.draw
+      end
     end # class YTick
   end # module Artist
 end # module Rubyplot

spec/axes_spec.rb

@@ -31,12 +31,13 @@
           axes.stacked_bar! do |p|
             p.data data
             p.label = label
-          end          
+          end
         end
         axes.title = "net earnings in different months."
         axes.x_ticks = ['Jan', 'Feb', 'March', 'April', 'May', 'June',  'July',
                         'August', 'September', 'October', 'November', 'December']
-
+        axes.y_ticks = ['5', '10', '15', '20', '25', '30']
+
         file = "/#{Rubyplot.backend}_multiple_stacked_bar.png"
         fig.write(@temp_dir + file)