sampledrate.py

import time
import operator
import collections

class SampledRate(object):
    """Tool for pushing rate over time data"""
    
    def __init__(self, frequency=1, resolution=1, callback=None):
        """ frequency:  Rate update frequency in seconds
            resolution: Interval to average data over in seconds
            callback:   Optional callback when frequency is updated"""
        self.frequency  = frequency
        self.resolution = resolution
        self.callback   = callback
        self.samples    = collections.defaultdict(int)
        self.last_start = None
        self.last_value = 0 
    
    def tick(self, ticks=1):
        if not self.last_start:
            self.last_start = int(time.time())
        if int(time.time() - self.last_start) > self.frequency:
            # Add empty samples
            for x in range(self.frequency-len(self.samples)):
                self.samples[x] = 0
            self.last_value = reduce(operator.add, self.samples.values()) / self.resolution / self.frequency
            self.last_start = int(time.time())
            self.samples    = collections.defaultdict(int)
            if self.callback:
                self.callback(self.last_value)
        self.samples[int(time.time() / self.resolution)] += ticks
        return self
    
    def value(self):
        return self.last_value
    
    def __int__(self):
        return self.last_value
    
    def __repr__(self):
        return "<SampledRate: %i  avg/%is updated/%is>" % (self.last_value, self.frequency, self.resolution)