exponential trend example grafica

external_library/java/grafica/exponential_trend.rb

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+# frozen_string_literal: true
+
+load_library 'grafica'
+java_import 'grafica.GPointsArray'
+java_import 'grafica.GPlot'
+java_import 'java.util.Random'
+
+N_POINTS = 1_000
+attr_reader :plot, :log_scale, :random, :points
+
+def settings
+  size(450, 450)
+end
+
+def setup
+  sketch_title 'Exponential Trend'
+  @random = Random.new
+  # Prepare the points for the plot
+  @points = GPointsArray.new(N_POINTS)
+  @plot = GPlot.new(self)
+  puts plot.inspect
+  @log_scale = false
+  N_POINTS.times do
+    x_value = rand(10..200)
+    y_value = 10**(0.015 * x_value)
+    x_error = 2 * random.next_gaussian
+    y_error = 2 * random.next_gaussian
+    points.add(x_value + x_error, y_value + y_error)
+  end
+  # Create the plot
+  plot.set_pos(25, 25)
+  plot.set_dim(300, 300)
+  # or all in one go
+  # plot = GPlot.new(self, 25, 25, 300, 300)
+  # Set the plot title and the axis labels
+  plot.set_title_text('Exponential law')
+  # NB: cannot use snake for getXAxis etc
+  plot.getXAxis.set_axis_label_text('x')
+  toggle_y_axis
+  # Add the points to the plot
+  plot.set_points(points)
+  plot.set_point_color(color(100, 100, 255, 50))
+end
+
+def draw
+  background(150)
+  plot.begin_draw
+  plot.draw_background
+  plot.draw_box
+  plot.drawXAxis
+  plot.drawYAxis
+  plot.draw_top_axis
+  plot.draw_right_axis
+  plot.draw_title
+  plot.draw_points
+  plot.end_draw
+end
+
+def toggle_y_axis
+  y_axis = plot.getYAxis
+  if log_scale
+    plot.set_log_scale('y')
+    y_axis.set_axis_label_text('log y')
+  else
+    plot.set_log_scale('')
+    y_axis.set_axis_label_text('y')
+  end  
+end
+
+def mouse_clicked
+  @log_scale = !log_scale
+  toggle_y_axis
+end