data_collector.py 文件源码

def _encode_ratio(inval, outval):
        '''
        Calculate the log ratio between inbound and outbound traffic.
        Positive when outval > inval, and negative when inval > outval.
        Returns a non-infinite floating point value:
        - zero when inval and outval are zero,
        - a large negative number (< -100) when outval is zero, and
        - a large positive number (> 100) when inval is zero, and
        - log(base 2)(outval/inval) otherwise.
        '''
        inval = float(inval)
        outval = float(outval)
        if inval == 0.0 and outval == 0.0:
            return 0.0
        elif inval == 0.0:
            return sys.float_info.max_exp
        elif outval == 0.0:
            return sys.float_info.min_exp
        else:
            return math.log(outval/inval, 2)