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python-3.x - Python解析XML文件时如何解决Key Error

问题描述

我有以下 XML 文件，我想将其转换为 Pandas DataFrame。

row {'Id': '-1', 'Reputation': '1', 'CreationDate': '2009-09-28T00:00:00.000', 'DisplayName': 'Community', 'LastAccessDate': '2010-11-10T17:25:34.627', 'WebsiteUrl': 'http://meta.stackexchange.com/', 'Location': 'on the server farm', 'AboutMe': '<p>Hi, I\'m not really a person.</p>\n\n<p>I\'m a background process that helps keep this site clean!</p>\n\n<p>I do things like</p>\n\n<ul>\n<li>Randomly poke old unanswered questions every hour so they get some attention</li>\n<li>Own community questions and answers so nobody gets unnecessary reputation from them</li>\n<li>Own downvotes on spam/evil posts that get permanently deleted</li>\n<li>Own suggested edits from anonymous users</li>\n<li><a href="http://meta.stackexchange.com/a/92006">Remove abandoned questions</a></li>\n</ul>\n', 'Views': '0', 'UpVotes': '21001', 'DownVotes': '27468', 'AccountId': '-1'}
row {'Id': '1', 'Reputation': '21228', 'CreationDate': '2009-09-28T14:35:46.490', 'DisplayName': 'Anton Geraschenko', 'LastAccessDate': '2020-05-17T06:51:32.333', 'WebsiteUrl': 'http://stacky.net', 'Location': 'Palo Alto, CA, United States', 'AboutMe': '<p>You can get in touch with me at geraschenko@gmail.com.</p>\n', 'Views': '25360', 'UpVotes': '1052', 'DownVotes': '90', 'AccountId': '36500'}

以下代码适用于几乎相同的 XML 文件，但是当我将它用于此文件时，我收到错误：

代码

users_tree = ET.parse("/content/Users.xml")
users_root = users_tree.getroot()

file_path_users = r"/content/Users.xml"
dict_list_users = []

for _, elem in ET.iterparse(file_path_users, events=("end",)):
    if elem.tag == "row":
        dict_list_users.append({'UserId': elem.attrib['Id'],
                          'Reputation': elem.attrib['Reputation'],
                          'CreationDate': elem.attrib['CreationDate'],
                          'DisplayName': elem.attrib['DisplayName'],
                          'LastAccessDate': elem.attrib['LastAccessDate'],
                          'WebsiteUrl': elem.attrib['WebsiteUrl'],
                          'Location': elem.attrib['Location'],
                          'AboutMe': elem.attrib['AboutMe'],
                          'Views': elem.attrib['Views'],
                          'UpVotes': elem.attrib['UpVotes'],
                          'DownVotes': elem.attrib['DownVotes'],
                          'AccountId': elem.attrib['AccountId']})
elem.clear()

df_users = pd.DataFrame(dict_list_users)

错误

KeyError                                  Traceback (most recent call last)
<ipython-input-18-7af87798bae8> in <module>()
     24                           'DisplayName': elem.attrib['DisplayName'],
     25                           'LastAccessDate': elem.attrib['LastAccessDate'],
---> 26                           'WebsiteUrl': elem.attrib['WebsiteUrl'],
     27                           'Location': elem.attrib['Location'],
     28                           'AboutMe': elem.attrib['AboutMe'],

KeyError: 'WebsiteUrl'

注意：LastAccessDate 之后的所有属性都会出现此错误，即，即使我删除了 WebsiteUrl 键，我也会收到下一个属性的错误，依此类推。

请为我提供解决此问题的方法。

标签： python-3.xxmlpandasdataframexml-parsing

解决方案

错误似乎是由于一个或多个<row>标签中缺少属性。考虑检索所有属性，而不是通过每个属性显式分配字典键/值。这样做，最终的DataFrame构造函数将输入NAs到缺少属性的行。

for _, elem in ET.iterparse(file_path_users, events=("end",)):
    if elem.tag == "row":
        dict_list_users.append(elem.attrib)    # RETRIEVE ALL ATTRIBUTES

        elem.clear()                           # SHOULD BE AT NESTED LEVEL

df_users = pd.DataFrame(dict_list_users)

如果上面的列比需要的多，请仅保留相关列reindex：

df_users = df_users.reindex(
    ['UserId', 'Reputation', 'CreationDate', 'DisplayName',
    'LastAccessDate', 'WebsiteUrl', 'Location', 'AboutMe',
    'Views', 'UpVotes', 'DownVotes', 'AccountId'],
    axis='columns'
)

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