Python仍然存在try-except子句的问题[重复]答案

【问题标题】：Python still having issues with try-except clause [duplicate]Python仍然存在try-except子句的问题[重复]
【发布时间】：2019-05-07 03:22:03
【问题描述】：

我正在使用 tld python 库使用 apply 函数从代理请求日志中获取第一级域。当我遇到一个 tld 不知道如何处理的奇怪请求时，例如“http:1 CON”或“http:/login.cgi%00”，我遇到如下错误消息：

TldBadUrl: Is not a valid URL http:1 con!
TldBadUrlTraceback (most recent call last)
in engine
----> 1 new_fld_column = request_2['request'].apply(get_fld)

/usr/local/lib/python2.7/site-packages/pandas/core/series.pyc in apply(self, func, convert_dtype, args, **kwds)
   2353             else:
   2354                 values = self.asobject
-> 2355                 mapped = lib.map_infer(values, f, convert=convert_dtype)
   2356 
   2357         if len(mapped) and isinstance(mapped[0], Series):

pandas/_libs/src/inference.pyx in pandas._libs.lib.map_infer (pandas/_libs/lib.c:66440)()

/home/cdsw/.local/lib/python2.7/site-packages/tld/utils.pyc in get_fld(url, 
fail_silently, fix_protocol, search_public, search_private, **kwargs)
    385         fix_protocol=fix_protocol,
    386         search_public=search_public,
--> 387         search_private=search_private
    388     )
    389 

/home/cdsw/.local/lib/python2.7/site-packages/tld/utils.pyc in process_url(url, fail_silently, fix_protocol, search_public, search_private)
    289             return None, None, parsed_url
    290         else:
--> 291             raise TldBadUrl(url=url)
    292 
    293     domain_parts = domain_name.split('.')

为了克服这个问题，有人建议我将该函数包装在一个 try-except 子句中，以通过使用 NaN 查询它们来确定出错的行：

import tld
from tld import get_fld

def try_get_fld(x):
    try: 
        return get_fld(x)
    except tld.exceptions.TldBadUrl: 
        return np.nan

这似乎适用于某些“请求”，例如“http:1 con”和“http:/login.cgi%00”，但随后对于“http://urnt12.knhc..txt/”失败，我收到另一条类似的错误消息以上：

TldDomainNotFound: Domain urnt12.knhc..txt didn't match any existing TLD name!

这是一个名为“请求”的数据帧中总共有 240,000 个“请求”的数据帧的样子：

request
  request                                      count
0 https://login.microsoftonline.com            24521
1 https://dt.adsafeprotected.com               11521
2 https://googleads.g.doubleclick.net          6252
3 https://fls-na.amazon.com                    65225
4 https://v10.vortex-win.data.microsoft.com    7852222
5 https://ib.adnxs.com                         12
6 http:1 CON                                   6 
7 http:/login.cgi%00                           45822
8 http://urnt12.knhc..txt/                     1

我的代码：

from tld import get_tld
from tld import get_fld
import pandas as pd
import numpy as np
#Read back into to dataframe
request = pd.read_csv('Proxy/Proxy_Analytics/Request_Grouped_By_Request_Count_12032018.csv')
#Remove rows where there were null values in the request column 
request = request[pd.notnull(request['request'])]
#Find the urls that contain IP addresses and exclude them from the new dataframe
request = request[~request.request.str.findall(r'[0-9]+(?:\.[0-9]+){3}').astype(bool)]
#Reset index
request = request.reset_index(drop=True)

import tld
from tld import get_fld

def try_get_fld(x):
    try: 
        return get_fld(x)
    except tld.exceptions.TldBadUrl: 
        return np.nan

request['flds'] = request['request'].apply(try_get_fld)

#faulty_url_df = request[request['flds'].isna()]
#print(faulty_url_df)

【问题讨论】：

我会先尝试一个通用的异常捕获器。 like except Exception as e: 确保它不是您预期的 tld.exceptions.TldBadUrl 以外的其他异常。

标签： python pandas dataframe apply

【解决方案1】：

它失败，因为它是一个不同的例外。你 expect 一个 tld.exceptions.TldBadUrl: 异常但得到一个 TldDomainNotFound

您可以在您的 except 子句中不那么具体，并使用一个 except 子句捕获更多异常，或者添加另一个 except 子句来捕获其他类型的异常：

try: 
    return get_fld(x)
except tld.exceptions.TldBadUrl: 
    return np.nan
except tld.exceptions.TldDomainNotFound:
    print("Domain not found!")
    return np.nan

【讨论】：