Class: Gruff::Line

Inherits:
Base
  • Object
show all
Defined in:
lib/gruff/line.rb

Overview

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.

Constant Summary

Constants inherited from Base

Base::DATA_COLOR_INDEX, Base::DATA_LABEL_INDEX, Base::DATA_VALUES_INDEX, Base::DEBUG, Base::DEFAULT_MARGIN, Base::DEFAULT_TARGET_WIDTH, Base::LABEL_MARGIN, Base::LEGEND_MARGIN, Base::THOUSAND_SEPARATOR

Instance Attribute Summary collapse

Attributes inherited from Base

#additional_line_values, #bottom_margin, #center_labels_over_point, #colors, #font, #font_color, #has_left_labels, #hide_legend, #hide_line_markers, #hide_line_numbers, #hide_title, #labels, #left_margin, #legend_box_size, #legend_font_size, #legend_margin, #marker_color, #marker_count, #marker_font_size, #maximum_value, #minimum_value, #no_data_message, #right_margin, #sort, #stacked, #title, #title_font_size, #title_margin, #top_margin, #x_axis_label, #y_axis_increment, #y_axis_label

Instance Method Summary collapse

Methods inherited from Base

#add_color, #data, #initialize_ivars, #margins=, #replace_colors, #theme=, #theme_37signals, #theme_greyscale, #theme_keynote, #theme_odeo, #theme_pastel, #theme_rails_keynote, #to_blob, #write

Methods included from Deprecated

#graph_height, #graph_left, #graph_top, #graph_width, #scale_measurements, #total_height

Constructor Details

#initialize(*args) ⇒ Line

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.

Raises:

  • (ArgumentError) 


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# 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

Instance Attribute Details

#baseline_color ⇒ Object

Color of the baseline



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# File 'lib/gruff/line.rb', line 21

def baseline_color
  @baseline_color
end

#baseline_value ⇒ Object

Draw a dashed line at the given value



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# File 'lib/gruff/line.rb', line 18

def baseline_value
  @baseline_value
end

#dot_radius ⇒ Object

Returns the value of attribute dot_radius.



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# File 'lib/gruff/line.rb', line 25

def dot_radius
  @dot_radius
end

#hide_dots ⇒ Object

Hide parts of the graph to fit more datapoints, or for a different appearance.



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# File 'lib/gruff/line.rb', line 28

def hide_dots
  @hide_dots
end

#hide_lines ⇒ Object

Hide parts of the graph to fit more datapoints, or for a different appearance.



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# File 'lib/gruff/line.rb', line 28

def hide_lines
  @hide_lines
end

#line_width ⇒ Object

Dimensions of lines and dots; calculated based on dataset size if left unspecified



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# File 'lib/gruff/line.rb', line 24

def line_width
  @line_width
end

Instance Method Details

#contains_one_point_only?(data_row) ⇒ Boolean

Returns:

  • (Boolean) 


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# 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

#draw ⇒ Object 



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# 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

#normalize ⇒ Object 



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# File 'lib/gruff/line.rb', line 112

def normalize
  @maximum_value = [@maximum_value.to_f, @baseline_value.to_f].max
  super
  @norm_baseline = (@baseline_value.to_f / @maximum_value.to_f) if @baseline_value
end