Class: Shades::StreamReservoir

Inherits:
Object
  • Object
show all
Defined in:
lib/shades/histo.rb

Instance Method Summary collapse

Constructor Details

#initialize(max_size) ⇒ StreamReservoir

Returns a new instance of StreamReservoir.



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# File 'lib/shades/histo.rb', line 34

def initialize(max_size)
  @max_size = max_size
  @n = 0
  @bins = []
end

Instance Method Details

#add(bin) ⇒ Object 



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# File 'lib/shades/histo.rb', line 40

def add(bin)
  @n += bin.count
  # bind the bin index to place this data
  i = placement(bin)
  @bins.insert(i, bin)
end

#compress ⇒ Object 



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# File 'lib/shades/histo.rb', line 56

def compress
  while @bins.length > @max_size
    min_gap_index = -1
    min_gap = Float::MAX
    # find the bin covering the smallest range
    (@bins.length-1).times do |i|
      bin_a = @bins[i]
      bin_b = @bins[i+1]
      gap = bin_b.mean - bin_a.mean
      if min_gap > gap
        min_gap = gap
        min_gap_index = i
      end
    end
    # and merge that bin with the one to its right
    prevbin = @bins[min_gap_index]
    nextbin = @bins.delete_at(min_gap_index+1)
    prevbin.merge(nextbin)
  end
end

#histo_text(output_width) ⇒ Object

outputs a histogram of the form 0.502 ( 27) ############################## 1.108 ( 14) ############### 1.731 ( 7) ####### 2.343 ( 3) ### 3.138 ( 4) #### 3.968 ( 6) ###### 4.548 ( 4) #### 5.225 ( 2) ## 5.990 ( 2) ## 8.720 ( 1) #

So, the line above that reads “0.502 ( 27) ##############################” can be read as: “There are 27 values close to 0.502”



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# File 'lib/shades/histo.rb', line 99

def histo_text(output_width)
  a = []
  max_bin_count = 1
  @bins.each do |b|
    if b.count > max_bin_count
      max_bin_count = b.count
    end
  end
  scaled_max = yield max_bin_count
  @bins.each do |b|
    scaled_value = yield b.count
    repeat = (output_width * ( Float(scaled_value) / Float(scaled_max) )).to_i
    a << "%14.3f (%5d) %s" % [b.mean, b.count, '#' * repeat]
  end
  a.join("\n")
end

#lines ⇒ Object 



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# File 'lib/shades/histo.rb', line 77

def lines
  a = []
  @bins.each do |b|
    a << "%8d %10.4f" % [b.count, b.mean]
  end
  a.join("\n")
end

#placement(bin) ⇒ Object 



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# File 'lib/shades/histo.rb', line 47

def placement(bin)
  @bins.length.times do |i|
    if @bins[i].mean >= bin.mean
      return i
    end
  end
  return @bins.length
end