Initialize an Influxdb database client

def influx_init(self, url, port, user, pwd, db):
        """
        Initialize an Influxdb database client
        """
        try:
            cli = DataFrameClient(url, port, user, pwd, db)
            self.influx_cli = cli
        except Exception as e:
            self.err(e, self.influx_init,
                     "Can not initialize Influxdb database")