class Silicium::Plotter::Image

A class representing canvas for plotting bar charts and function graphs

Public Class Methods

new(width, height, bg_color = ChunkyPNG::Color::TRANSPARENT) click to toggle source

Creates a new plot with chosen width and height parameters with background colored bg_color

# File lib/plotter.rb, line 49
def initialize(width, height, bg_color = ChunkyPNG::Color::TRANSPARENT)
  @image = ChunkyPNG::Image.new(width, height, bg_color)
end

Public Instance Methods

bar_chart(bars, bar_width, bars_color = ChunkyPNG::Color('red @ 1.0'), axis_color = ChunkyPNG::Color::BLACK) click to toggle source

Draws a bar chart in the plot using provided bars, each of them has width of bar_width and colored bars_color

# File lib/plotter.rb, line 66
def bar_chart(bars, bar_width, bars_color = ChunkyPNG::Color('red @ 1.0'), axis_color = ChunkyPNG::Color::BLACK)
  if bars.count * bar_width > @image.width
    raise ArgumentError, 'Not enough big size of image to plot these number of bars'
  end

  padding = 5
  # Values of x and y on borders of plot
  minx = [bars.collect { |k, _| k }.min, 0].min
  maxx = [bars.collect { |k, _| k }.max, 0].max
  miny = [bars.collect { |_, v| v }.min, 0].min
  maxy = [bars.collect { |_, v| v }.max, 0].max
  dpux = Float((@image.width - 2 * padding)) / (maxx - minx + bar_width) # Dots per unit for X
  dpuy = Float((@image.height - 2 * padding)) / (maxy - miny) # Dots per unit for Y
  rectangle(padding, @image.height - padding - (miny.abs * dpuy).ceil, @image.width - 2 * padding, 1, axis_color) # Axis OX
  rectangle(padding + (minx.abs * dpux).ceil, padding, 1, @image.height - 2 * padding, axis_color) # Axis OY

  bars.each do |x, y| # Cycle drawing bars
    rectangle(padding + ((x + minx.abs) * dpux).floor,
              @image.height - padding - (([y, 0].max + miny.abs) * dpuy).ceil + (y.negative? ? 1 : 0),
              bar_width, (y.abs * dpuy).ceil, bars_color)
  end
end

export(filename) click to toggle source

Exports plotted image to file filename

# File lib/plotter.rb, line 91
def export(filename)
  @image.save(filename, :interlace => true)
end

rectangle(x, y, width, height, color) click to toggle source

# File lib/plotter.rb, line 53
def rectangle(x, y, width, height, color)
  x_end = x + width - 1
  y_end = y + height - 1
  (x..x_end).each do |i|
    (y..y_end).each do |j|
      @image[i, j] = color
    end
  end
end