Class: Statsample::Graph::Boxplot

Inherits:
Object
  • Object
show all
Includes:
Summarizable
Defined in:
lib/statsample/graph/boxplot.rb

Overview

Boxplot

From Wikipedia: In descriptive statistics, a box plot or boxplot (also known as a box-and-whisker diagram or plot) is a convenient way of graphically depicting groups of numerical data through their five-number summaries: the smallest observation (sample minimum), lower quartile (Q1), median (Q2), upper quartile (Q3), and largest observation (sample maximum). A boxplot may also indicate which observations, if any, might be considered outliers.

Usage

Svg output

a = Daru::Vector.new([1,2,3,4])
b = Daru::Vector.new([3,4,5,6])

puts Statsample::Graph::Boxplot.new(:vectors=>).to_svg

Using ReportBuilder

a = Daru::Vector.new([1,2,3,4])
b = Daru::Vector.new([3,4,5,6])
rb=ReportBuilder.new
rb.add(Statsample::Graph::Boxplot.new(:vectors=>[a,b]))
rb.save_html('boxplot.html')

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Summarizable

#summary

Constructor Details

#initialize(opts = Hash.new) ⇒ Boxplot

Create a new Boxplot. Parameters: Hash of options

  • :vectors: Array of vectors

  • :groups: Array of same size as :vectors:, with name of groups

    to colorize vectors



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# File 'lib/statsample/graph/boxplot.rb', line 58

def initialize(opts=Hash.new)
  @vectors=opts.delete :vectors
  raise "You should define vectors" if @vectors.nil?
  
  opts_default={
    :name=>_("Boxplot"),
    :groups=>nil,
    :width=>400,
    :height=>300,
    :margin_top=>10,
    :margin_bottom=>20,
    :margin_left=>20,
    :margin_right=>20,
    :minimum=>nil,
    :maximum=>nil,
    :label_angle=>0
  }
  @opts=opts_default.merge(opts)
  opts_default.keys.each {|k| send("#{k}=", @opts[k]) }
end

Instance Attribute Details

#groups ⇒ Object

Array with assignation to groups of bars For example, for four vectors, 

boxplot.groups=[1,2,1,3]

Assign same color to first and third element, and different to second and fourth



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# File 'lib/statsample/graph/boxplot.rb', line 41

def groups
  @groups
end

#height ⇒ Object

Total height of Boxplot



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# File 'lib/statsample/graph/boxplot.rb', line 27

def height
  @height
end

#label_angle ⇒ Object

The rotation angle, in radians. Text is rotated clockwise relative to the anchor location. For example, with the default left alignment, an angle of Math.PI / 2 causes text to proceed downwards. The default angle is zero.



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# File 'lib/statsample/graph/boxplot.rb', line 51

def label_angle
  @label_angle
end

#margin_bottom ⇒ Object

Bottom margin



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# File 'lib/statsample/graph/boxplot.rb', line 31

def margin_bottom
  @margin_bottom
end

#margin_left ⇒ Object

Left margin



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# File 'lib/statsample/graph/boxplot.rb', line 33

def margin_left
  @margin_left
end

#margin_right ⇒ Object

Right margin



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# File 'lib/statsample/graph/boxplot.rb', line 35

def margin_right
  @margin_right
end

#margin_top ⇒ Object

Top margin



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# File 'lib/statsample/graph/boxplot.rb', line 29

def margin_top
  @margin_top
end

#maximum ⇒ Object

Maximum value on y-axis. Automaticly defined from data



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# File 'lib/statsample/graph/boxplot.rb', line 45

def maximum
  @maximum
end

#minimum ⇒ Object

Minimum value on y-axis. Automaticly defined from data



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# File 'lib/statsample/graph/boxplot.rb', line 43

def minimum
  @minimum
end

#name ⇒ Object

Returns the value of attribute name.



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# File 'lib/statsample/graph/boxplot.rb', line 23

def name
  @name
end

#vectors ⇒ Object

Vectors to box-ploting



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# File 'lib/statsample/graph/boxplot.rb', line 47

def vectors
  @vectors
end

#width ⇒ Object

Total width of Boxplot



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# File 'lib/statsample/graph/boxplot.rb', line 25

def width
  @width
end

#x_scale ⇒ Object (readonly)

Returns the value of attribute x_scale.



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# File 'lib/statsample/graph/boxplot.rb', line 52

def x_scale
  @x_scale
end

#y_scale ⇒ Object (readonly)

Returns the value of attribute y_scale.



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# File 'lib/statsample/graph/boxplot.rb', line 52

def y_scale
  @y_scale
end

Instance Method Details

#report_building(builder) ⇒ Object

:nodoc:



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# File 'lib/statsample/graph/boxplot.rb', line 229

def report_building(builder) # :nodoc:
  builder.section(:name=>name) do |b|
    b.image(to_svg, :type=>'svg', :width=>width, :height=>height)
  end
end

#rubyvis_panel ⇒ Object

Returns a Rubyvis panel with scatterplot



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# File 'lib/statsample/graph/boxplot.rb', line 80

def rubyvis_panel # :nodoc:
  that=self
  
  min,max=@minimum, @maximum
  
  min||=@vectors.map {|v| v.min}.min
  max||=@vectors.map {|v| v.max}.max
  
  margin_hor=margin_left + margin_right
  margin_vert=margin_top  + margin_bottom
  x_scale = pv.Scale.ordinal(@vectors.size.times.map.to_a).split_banded(0, width-margin_hor, 4.0/5)
  y_scale=Rubyvis::Scale.linear(min,max).range(0,height-margin_vert)
  y_scale.nice
  # cache data
  
  colors=Rubyvis::Colors.category10
  
  data=@vectors.map {|v|
    out={:percentil_25=>v.percentil(25), :median=>v.median, :percentil_75=>v.percentil(75), :name=>v.name}
    out[:iqr]=out[:percentil_75] - out[:percentil_25]
    
    irq_max=out[:percentil_75] + out[:iqr]
    irq_min=out[:percentil_25] - out[:iqr]
    
    # Find the last data inside the margin
    min = out[:percentil_25]
    max = out[:percentil_75]
    
    v.each {|d|
      min=d if d < min and d > irq_min
      max=d if d > max and d < irq_max
    }
    # Whiskers!
    out[:low_whisker]=min
    out[:high_whisker]=max
    # And now, data outside whiskers
    out[:outliers]=v.to_a.find_all {|d| d < min or d > max }
    out
  }
         
  vis=Rubyvis::Panel.new do |pan| 
    pan.width  width  - margin_hor
    pan.height height - margin_vert
    pan.bottom margin_bottom
    pan.left   margin_left
    pan.right  margin_right
    pan.top    margin_top
     # Y axis
    pan.rule do
      data y_scale.ticks
      bottom y_scale
      stroke_style {|d| d!=0 ? "#eee" : "#000"}
      label(:anchor=>'left') do
        text y_scale.tick_format
      end
    end
    pan.rule do
      bottom 0
      stroke_style 'black'
    end
    
    # Labels
    
    pan.label  do |l|
      l.data data
      l.text_angle that.label_angle
      l.left  {|v| x_scale[index] }
      l.bottom(-15)
      l.text {|v,x| v[:name]}
    end
    
    pan.panel do |bp|
      bp.data data
      bp.left {|v|  x_scale[index]}
      bp.width x_scale.range_band
      
      # Bar
      bp.bar do |b|
        b.bottom {|v| y_scale[v[:percentil_25]]}
        b.height {|v| y_scale[v[:percentil_75]] - y_scale[v[:percentil_25]] }
        b.line_width 1
        b.stroke_style  {|v| 
          if that.groups
            colors.scale(that.groups[parent.index]).darker
          else
            colors.scale(index).darker
          end  
        }
        b.fill_style {|v| 
          if that.groups
            colors.scale(that.groups[parent.index])
          else
            colors.scale(index)
          end
        }
      end
      # Median
      bp.rule do |r|
        r.bottom {|v| y_scale[v[:median]]}
        r.width x_scale.range_band
        r.line_width 2
      end
      ##
      # Whiskeys
      ##
      # Low whiskey
      bp.rule do |r|
        r.visible {|v| v[:percentil_25] > v[:low_whisker]}
        r.bottom {|v| y_scale[v[:low_whisker]]}              
      end
      
      bp.rule do |r|
        r.visible {|v| v[:percentil_25] > v[:low_whisker]}
        r.bottom {|v| y_scale[v[:low_whisker]]}              
        r.left {|v| x_scale.range_band / 2.0}
        r.height {|v| y_scale.scale(v[:percentil_25]) - y_scale.scale(v[:low_whisker])}
      end
      # High whiskey

      bp.rule do |r|
        r.visible {|v| v[:percentil_75] < v[:high_whisker]}
        r.bottom {|v| y_scale.scale(v[:high_whisker])}              
      end
      
       bp.rule do |r|
        r.visible {|v| v[:percentil_75] < v[:high_whisker]}
        r.bottom {|v| y_scale.scale(v[:percentil_75])}              
        r.left {|v| x_scale.range_band / 2.0}
        r.height {|v| y_scale.scale(v[:high_whisker]) - y_scale.scale(v[:percentil_75])}
      end
      # Outliers
      bp.dot do |dot|
        dot.shape_size 4
        dot.data {|v| v[:outliers]}
        dot.left {|v| x_scale.range_band / 2.0}
        dot.bottom {|v| y_scale.scale(v)}
        dot.title {|v| v}
      end
    end
  end
  vis
end

#to_svg ⇒ Object

Returns SVG with scatterplot



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# File 'lib/statsample/graph/boxplot.rb', line 224

def to_svg
  rp=rubyvis_panel
  rp.render
  rp.to_svg
end