AverageStack.py

from __future__ import division

class AverageStack:

    """Use it to smooth values over time.

    When you add a new value, the oldest value gets overwritten.
    Returns the average of the remaining values.

    You can add any type as long as it supports __add__ in a numeric way.
    Will return a float.

    """


    def __init__(self, dim, default=0):

        """dim is the size of the stack: how many values to store
        before starting to overwrite. default is the default value
        the stack is filled with at start."""

        self._data = [default] * dim
        self._pos = 0
        self._dim = dim


    def add(self, value):

        """Adds value to the stack and advances internal pointer."""

        self._data[self._pos] = value
        self._pos += 1
        if self._pos >= self._dim:
            self._pos = 0


    def avg(self, value=None):

        """Calculates the average of all values currently in stock.
        This also includes the default values not yet overwritten.
        You can add a value as the first parameter to add it to stack
        before calculating the average."""

        if value is not None:
            self.add(value)

        return sum(self._data) / self._dim


    def dump(self):

        """Just gets you some info for debugging."""

        print "data:" ,
        for i in range(self._dim):
            print self._data[i] ,
        print ""
        print " avg:" , self.avg()
        print " pos:" , self._pos
        print " dim:" , self._dim

# eof