Module: Enumerable

Defined in:
lib/nobiru/extensions/enumerable_extension.rb

Instance Method Summary collapse

Instance Method Details

#drop_last(n) ⇒ Object 



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# File 'lib/nobiru/extensions/enumerable_extension.rb', line 9

def drop_last(n)
  array = to_a

  return array if n > array.size
  array[0...(array.size - n)]
end

#drop_last_while ⇒ Object 



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# File 'lib/nobiru/extensions/enumerable_extension.rb', line 16

def drop_last_while
  return to_enum(:drop_last_while) unless block_given?

  result   = []
  dropping = true
  reverse_each do |value|
    result.unshift(value) unless dropping &&= yield(value)
  end
  result
end

#exactly?(n) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/nobiru/extensions/enumerable_extension.rb', line 27

def exactly?(n)
  found_count = 0

  if block_given?
    each do |*o|
      found_count += 1 if yield(*o)
    end
  else
    each do |o|
      found_count += 1 if o
    end
  end

  (found_count > n) ? false : n == found_count
end

#frequencies ⇒ Object 



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# File 'lib/nobiru/extensions/enumerable_extension.rb', line 43

def frequencies
  each_with_object(Hash.new(0)) { |e, a| a[e] += 1 }
end

#max(identity = 0) ⇒ Object 



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# File 'lib/nobiru/extensions/enumerable_extension.rb', line 47

def max(identity=0)
  size > 0 ? sort.last : identity
end

#mean(identity = 0) ⇒ Object 



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# File 'lib/nobiru/extensions/enumerable_extension.rb', line 55

def mean(identity=0)
  collection_size = size
  collection_size > 0 ? inject(:+) / collection_size.to_f : identity
end

#median(identity = 0) ⇒ Object 



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# File 'lib/nobiru/extensions/enumerable_extension.rb', line 60

def median(identity=0)
  collection_size   = size
  collection_sorted = sort

  if collection_size > 0
    if collection_size % 2 == 0
      (collection_sorted[(collection_size / 2) -1] + collection_sorted[collection_size / 2]) / 2.0
    else
      collection_sorted[collection_size / 2]
    end
  else
    identity
  end
end

#min(identity = 0) ⇒ Object 



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# File 'lib/nobiru/extensions/enumerable_extension.rb', line 51

def min(identity=0)
  size > 0 ? sort.first : identity
end

#mode(identity = 0) ⇒ Object 



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# File 'lib/nobiru/extensions/enumerable_extension.rb', line 75

def mode(identity=0)
  if size > 0
    frequency_distribution = inject(Hash.new(0)) { |h, v| h[v] += 1; h }
    frequency_top_2        = frequency_distribution.sort { |a, b| b[1] <=> a[1] }.take(2)

    if frequency_top_2.length == 1
      frequency_top_2.first.first
    elsif frequency_top_2.first.last == frequency_top_2.last.last
      nil
    else
      frequency_top_2.first.first
    end
  else
    identity
  end
end

#range(identity = 0) ⇒ Object 



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# File 'lib/nobiru/extensions/enumerable_extension.rb', line 92

def range(identity=0)
  collection_sorted = sort
  size > 0 ? collection_sorted.last - collection_sorted.first : identity
end

#several? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/nobiru/extensions/enumerable_extension.rb', line 97

def several?
  found_count = 0

  if block_given?
    each do |*o|
      found_count += 1 if yield(*o)
    end
  else
    each do |o|
      found_count += 1 if o
    end
  end

  (found_count > 1) ? true : false
end

#standard_deviation ⇒ Object 



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# File 'lib/nobiru/extensions/enumerable_extension.rb', line 113

def standard_deviation
  return 0 if length < 2
  Math.sqrt(variance)
end

#sum(identity = 0) ⇒ Object 



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# File 'lib/nobiru/extensions/enumerable_extension.rb', line 4

def sum(identity=0)
  inject(:+) || identity
end

#take_last(n) ⇒ Object 



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# File 'lib/nobiru/extensions/enumerable_extension.rb', line 118

def take_last(n)
  array = to_a

  return array if n > array.size
  array[(array.size - n)..-1]
end

#take_last_while ⇒ Object 



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# File 'lib/nobiru/extensions/enumerable_extension.rb', line 125

def take_last_while
  return to_enum(:take_last_while) unless block_given?

  result = []
  reverse_each { |e| yield(e) ? result.unshift(e) : break }
  result
end

#variance ⇒ Object 



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# File 'lib/nobiru/extensions/enumerable_extension.rb', line 133

def variance
  collection_length = length

  return 0 if collection_length <= 1
  sum = inject(0) { |accumulator, value| accumulator + (value - mean) ** 2 }
  sum / (collection_length.to_f - 1)
end