python – Pandas DataFrame apply()ValueError：解压缩的值太多

以下是一种方法示例,其中包含“次优”一词.
虽然这对我相对较小的数据集来说已经足够了,但我想知道如何更好地编写它？

import pandas as pd
from pandas import DataFrame

# create sample log data frame
lg = pd.DataFrame(['Access violation at address 00A97...','Try to edit the splines or change...','Access violation at address 00F2B...','Please make sure the main electro...'],columns=['lg_msg'])

# define message classification
err_messages = [['Access violation','ACC-VIOL','PROG'],['Please make sure th','ELE-NOT-PLACED','MOD'],['Try to edit the splines','TRY-EDIT-SPLINES','MOD']]                

# lookup code
def message_code(msg_text):
    for msg in err_messages:
        if msg_text.startswith(msg[0]):
            return msg[1]
    return ''

# lookup type
def message_type(msg_text):
    for msg in err_messages:
        if msg_text.startswith(msg[0]):
            return msg[2]
    return ''               

lg['msg_code'] = lg['lg_msg'].apply(lambda x:  message_code(x))
lg['msg_type'] = lg['lg_msg'].apply(lambda x:  message_type(x))

我尝试创建一个函数来计算日志条目代码并立即输入：

def message_code_type(msg_text):
    for msg in err_messages:
        if msg_text.startswith(msg[0]):
            return (msg[1],msg[2])
    return ('','')

lg['msg_code'],lg['msg_type'] = lg['lg_msg'].apply(lambda x:  message_code_type(x))

但得到：

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-18-72f97d857539> in <module>()
----> 1 lg['msg_code'],lg['msg_code'] = lg['lg_msg'].apply(lambda x:  message_code_type(x))

ValueError: too many values to unpack (expected 2)

有没有办法不两次遍历数据帧？

任何反馈将不胜感激.

import sys
print(sys.version)
3.5.1 |Anaconda 2.4.0 (64-bit)| (default,Jan 29 2016,15:01:46) [MSC v.1900 64 bit (AMD64)]

pd.__version__
'0.17.1'