Class: Odds

Inherits:
Object
  • Object
show all
Includes:
FromHash
Defined in:
lib/odds/odds.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(arg) ⇒ Odds

Returns a new instance of Odds.



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# File 'lib/odds/odds.rb', line 5

def initialize(arg)
  if arg.kind_of?(Hash)
    from_hash(arg)
  else
    self.win_chance = arg
  end
end

Instance Attribute Details

#win_chance ⇒ Object

Returns the value of attribute win_chance.



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# File 'lib/odds/odds.rb', line 3

def win_chance
  @win_chance
end

Class Method Details

.from_string(str) ⇒ Object 



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# File 'lib/odds/odds.rb', line 61

def from_string(str)
  sign = str[0..0]
  num = str[1..-1].to_f / 100.0
  if sign == '-'
    from_win_amount_without_principal(1.0 / num)
  elsif sign == '+'
    from_win_amount_without_principal(num)
  else
    raise "bad #{str}"
  end
end

.from_win_amount_without_principal(num) ⇒ Object 



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# File 'lib/odds/odds.rb', line 72

def from_win_amount_without_principal(num)
  new(:win_chance => (1.0 / (1.0 + num)))
end

Instance Method Details

#*(other) ⇒ Object 



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# File 'lib/odds/odds.rb', line 43

def* (other)
  res = win_chance * other.win_chance
  self.class.new(:win_chance => res)
end

#inverse ⇒ Object 



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# File 'lib/odds/odds.rb', line 48

def inverse
  self.class.new(:win_chance => (1.0 - win_chance))
end

#log_odds ⇒ Object 



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# File 'lib/odds/odds.rb', line 56

def log_odds
  Math.log(odds)
end

#loss_chance ⇒ Object 



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# File 'lib/odds/odds.rb', line 37

def loss_chance
  1.0 - win_chance
end

#odds ⇒ Object 



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# File 'lib/odds/odds.rb', line 52

def odds
  win_chance / (1.0 - win_chance)
end

#to_s ⇒ Object 



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# File 'lib/odds/odds.rb', line 13

def to_s
  if win_chance < 0.5
    "+" + (win_amount_without_principal * 100.0).to_i.to_s
  else
    n = (1.0 / loss_chance) - 1.0
    "-" + (n * 100.0).to_i.to_s
  end
end

#to_s_to_one ⇒ Object 



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# File 'lib/odds/odds.rb', line 22

def to_s_to_one
  if win_chance < 0.5
    "#{win_amount_without_principal} to 1"
  else
    n = (1.0 / win_amount_without_principal).round(1)
    "1 to #{n}"
  end
end

#win_amount_with_principal ⇒ Object 



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# File 'lib/odds/odds.rb', line 31

def win_amount_with_principal
  1.0 / win_chance
end

#win_amount_without_principal ⇒ Object 



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# File 'lib/odds/odds.rb', line 34

def win_amount_without_principal
  win_amount_with_principal - 1.0
end