class_docstr: Running mean calculator.
  
  This class can be used to calculate the mean of elements from a
  list, tuple, iterable or any other data source. The mean is
  calculated on the fly without explicitly summing the values,
  so it can be used for data sets with arbitrary item count. Also
  capable of returning the standard deviation (also calculated on
  the fly)
docstr: RunningMean.add(value, repeat=1)
  
  Adds the given value to the elements from which we calculate
  the mean and the standard deviation.
  
  @param value: the element to be added
  @param repeat: number of repeated additions
docstr_tok: ["RunningMean.add","(","value",",","repeat=1",")","Adds","the","given","value","to","the","elements","from","which","we","calculate","the","mean","and","the","standard","deviation",".","@","param","value",":","the","element","to","be","added","@","param","repeat",":","number","of","repeated","additions"]
code: def add(self, value, repeat=1):
      """RunningMean.add(value, repeat=1)
  
      Adds the given value to the elements from which we calculate
      the mean and the standard deviation.
  
      @param value: the element to be added
      @param repeat: number of repeated additions
      """
      repeat = int(repeat)
      self._nitems += repeat
      delta = value - self._mean
      self._mean += repeat * delta / self._nitems
      self._sqdiff += (repeat * delta) * (value - self._mean)
      if self._nitems > 1:
          self._sd = (self._sqdiff / (self._nitems - 1)) ** 0.5
  
imports: import math
label_desc: Use image node_id 2 for calling the RunningMean obj's underlying member method code with example usage: obj.add(value, repeat) without return types