Class: Sbn::Combination

Inherits:
Object show all
Includes:
Enumerable
Defined in:
lib/sbn/combination.rb

Overview

:nodoc:

Instance Method Summary collapse

Methods included from Enumerable

#average, #sample_variance, #standard_deviation, #sum

Constructor Details

#initialize(arr) ⇒ Combination

Returns a new instance of Combination.



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# File 'lib/sbn/combination.rb', line 23

def initialize(arr)
  @arr = arr
  @current = Array.new(arr.size, 0)
end

Instance Method Details

#<=>(other) ⇒ Object 



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# File 'lib/sbn/combination.rb', line 34

def <=>(other)
  @current <=> other.current
end

#current ⇒ Object 



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# File 'lib/sbn/combination.rb', line 46

def current
  returnval = []
  @current.size.times {|i| returnval[i] = @arr[i][@current[i]] }
  returnval
end

#each {|current| ... } ⇒ Object

Yields:



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# File 'lib/sbn/combination.rb', line 28

def each
  iterations = @arr.inject(1) {|product, element| product * element.size } - 1
  yield current
  iterations.times { yield self.next_combination }
end

#first ⇒ Object 



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# File 'lib/sbn/combination.rb', line 38

def first
  @current.fill 0
end

#last ⇒ Object 



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# File 'lib/sbn/combination.rb', line 42

def last
  @current.size.times {|i| @current[i] = @arr[i].size - 1 }
end

#next_combination ⇒ Object 



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# File 'lib/sbn/combination.rb', line 52

def next_combination
  i = @current.size - 1
  @current.reverse.each do |e|
    if e == @arr[i].size - 1
      @current[i] = 0
    else
      @current[i] += 1
      break
    end
    i -= 1
  end
  current
end

#prev_combination ⇒ Object 



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# File 'lib/sbn/combination.rb', line 66

def prev_combination
  i = @current.size - 1
  @current.reverse.each do |e|
    if e == 0
      @current[i] = @arr[i].size - 1
    else
      @current[i] -= 1
      break
    end
    i -= 1
  end
  current
end