Class: Spark

Inherits:
Object
  • Object
show all
Defined in:
lib/spark_pr/spark.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options) ⇒ Spark

Returns a new instance of Spark.



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# File 'lib/spark_pr/spark.rb', line 7

def initialize(options)
  # process options
  o = options.inject({}) do |o, (key, value)|
    o[key.to_sym] = value ; o
  end
  [:height, :width, :step].each do |k|
    o[k] = o[k].to_i if o.has_key?(k)
  end
  [:has_min, :has_max, :has_last].each do |k|
    o[k] = (o[k] ? true : false) if o.has_key?(k)
  end
  o[:normalize] ||= :linear
  o[:normalize] = o[:normalize].to_sym

  self.opts = o
end

Instance Attribute Details

#canvas ⇒ Object

Returns the value of attribute canvas.



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# File 'lib/spark_pr/spark.rb', line 5

def canvas
  @canvas
end

#opts ⇒ Object

Returns the value of attribute opts.



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# File 'lib/spark_pr/spark.rb', line 5

def opts
  @opts
end

#png ⇒ Object

Returns the value of attribute png.



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# File 'lib/spark_pr/spark.rb', line 5

def png
  @png
end

Class Method Details

.data_uri(results, options = {}) ⇒ Object 



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# File 'lib/spark_pr/spark.rb', line 122

def self.data_uri( results, options = {} )
  spark = Spark.new(options)
  type = spark.opts.delete(:type) || :smooth
  spark.send(type, results)
  spark.data_uri
end

.plot(results, options = {}) ⇒ Object

convenience methods



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# File 'lib/spark_pr/spark.rb', line 116

def self.plot( results, options = {} )
  spark = Spark.new(options)
  type = spark.opts.delete(:type) || :smooth
  spark.send(type, results).to_png
end

Instance Method Details

#data_uri ⇒ Object 



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# File 'lib/spark_pr/spark.rb', line 111

def data_uri
  %{data:image/png;base64,#{Base64.encode64(png).gsub("\n",'')}}
end

#discrete(results) ⇒ Object 



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# File 'lib/spark_pr/spark.rb', line 81

def discrete( results )
  o = {
    :height => 14,
    :upper => 0.5,
    :has_min => false,
    :has_max => false
  }.merge(opts)

  o[:width] ||= results.size*2-1

  c = if o[:base_color]
        SparkCanvas.new(o[:width], o[:height], o[:base_color])
      else
        SparkCanvas.new(o[:width], o[:height])
      end

  results = normalize(results, o[:normalize])
  fac = c.height-4

  i = -2
  results.each do |r|
    p = c.height - 4 - r*fac
    c.color = r < o[:upper] ? [0x66,0x66,0x66,0xFF] : [0xFF,0x00,0x00,0xFF]
    c.line(i+=2, p, i, p+3)
  end

  self.png = c.to_png
  self.canvas = c
end

#normalize(arr, type = :linear) ⇒ Object

normalize arr to contain values between 0..1 inclusive



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# File 'lib/spark_pr/spark.rb', line 25

def normalize( arr, type = :linear )
  arr = arr.map { |v| v.to_f == 0.0 ? 0.0 : Math.log(v) } if type == :logarithmic

  return arr if array.min == array.max

  adj, fac = arr.min, arr.max-arr.min
  arr.map {|v| (v-adj).quo(fac) rescue 0 }
end

#smooth(results) ⇒ Object 



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# File 'lib/spark_pr/spark.rb', line 34

def smooth( results )
  o = {
    :step => 2,
    :height => 14,
    :has_min => false,
    :has_max => false
  }.merge(opts)

  o[:width] ||= (results.size-1)*o[:step] + 5

  c = if o[:base_color]
        SparkCanvas.new(o[:width], o[:height], o[:base_color])
      else
        SparkCanvas.new(o[:width], o[:height])
      end


  results = normalize(results, o[:normalize])
  fac = c.height-5
  i = -o[:step]
  coords = results.map do |r|
    [(i += o[:step])+2, c.height - 3 - r*fac ]
  end

  c.color = opts[:line_color] || [0xB0, 0xB0, 0xB0, 0xFF]
  c.polyline coords

  if o[:has_min]
    min_pt = coords[results.index(results.min)]
    c.color = [0x80, 0x80, 0x00, 0x70]
    c.rectangle(min_pt[0]-2, min_pt[1]-2, min_pt[0]+2, min_pt[1]+2)
  end

  if o[:has_max]
    max_pt = coords[results.index(results.max)]
    c.color = [0x00, 0x80, 0x00, 0x70]
    c.rectangle(max_pt[0]-2, max_pt[1]-2, max_pt[0]+2, max_pt[1]+2)
  end

  if o[:has_last]
    c.color = [0xFF, 0x00, 0x00, 0x70]
    c.rectangle(coords.last[0]-2, coords.last[1]-2, coords.last[0]+2, coords.last[1]+2)
  end
  self.png = c.to_png
  self.canvas = c
end