Playing with means

means.py

"""Playing with means.

Geometric and Arithmetric means will only ever be equal when every item on the
list is the same. So if you keep entering 2,2,2,2,2,2,etc the two averages will
be the same. As soon as a new value is in the list the two values will diverge.

You can use this to look at how much the values diverge by with the introduction of outliers.
"""

class MovingAvg(object):
  def __init__(self):
    self.numbers = []
    self.n = 0
    self.sum = 0
    self.mult = 1

  def AddInt(self, i):
    if i < 0:
      print("Can't insert negative value: {0}".format(i))
      return False  # Failed
    self.numbers.append(i)
    self.n += 1
    self.sum += i

    if i > 0:
      self.mult *= i
    return True  # Success

  def GetArithmeticMean(self):
    if self.n == 0:
      return 0
    return self.sum/float(self.n)

  def GetGeometricMean(self):
    if self.n == 0:
      return 0
    return self.mult**(1/float(self.n))

if __name__ == "__main__":
  calc = MovingAvg()
  while True:
    text = raw_input("Enter a number:")
    calc.AddInt(int(text))
    print("Numbers: {}".format(calc.numbers))
    print("Arithmetic Mean: {}".format(calc.GetArithmeticMean()))
    print("Geometric Mean: {}".format(calc.GetGeometricMean()))