Convert human-readable time ('1 min 3 sec', '0.58 hr', etc) to milliseconds

human_readable_time_to_ms.py

interval_dict = OrderedDict([
    ('hr', 3600*1000),
    ('min', 60*1000),
    ('sec', 1000),
    ('ms' , 1),
])

def convert_to_ms(string):
    interval_regex = re.compile( "^[<]?(?P<value>(\d\.)?[0-9]+) (?P<unit>({0}))".format("|".join(interval_dict.keys())) )

    milliseconds = 0
    while string:    
        match = interval_regex.match(string)
        if match:
            value, unit = float(match.group("value")), match.group("unit")
            if value == 0:
                return milliseconds
            if float(value) and unit in interval_dict:
                milliseconds += int(value * interval_dict[unit])
                string = string[match.end():].strip()
            else:
                raise Exception("Not a float value '{0}', or unable to find interval '{1}' for string '{2}'".format(value, unit, string))
        else:
            print "WARN:Unable to match string '{0}'".format(string)
            return -1.0
    return milliseconds