python3中解析XML模式的LXML问题

Question

我正试图使用XRDTools库将panalyticxrdml文件转换成更适合数据库的格式，比如pandas数据帧。在

XRDTools库描述如下：https://github.com/paruch-group/xrdtools。它将XRDML文件导入Python字典。我对LXML完全陌生，如果这是一个简单的问题，我很抱歉。在

我使用Anaconda创建了python2.7和3.6环境，专门用于使用XRDTools包。我想用python3.6运行它。在

在Python2.7中，此代码运行平稳：

import xrdtools
xrd = xrdtools.read_xrdml('filename.xrdml')

输出是dict：

^{pr2}$

然后我可以像使用其他Python对象一样使用字典。在

在Python3.6中，同样的代码会生成以下错误消息：

Traceback (most recent call last):

  File "...\AppData\Local\Continuum\Anaconda2\envs\py36xrd\lib\site-packages\IPython\core\interactiveshell.py", line 2910, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)

  File "<ipython-input-3-b6f5409b8bf9>", line 1, in <module>
    xrd = xrdtools.read_xrdml('filename.xrdml')

  File "...\XRDTools\xrdtools\xrdtools\io.py", line 297, in read_xrdml
    valid = validate_xrdml_schema(filename)

  File ...\XRDTools\xrdtools\xrdtools\io.py", line 43, in validate_xrdml_schema
    xmlschema_doc = etree.parse(f)

  File "src\lxml\etree.pyx", line 3444, in lxml.etree.parse (src\lxml\etree.c:83171)

  File "src\lxml\parser.pxi", line 1855, in lxml.etree._parseDocument (src\lxml\etree.c:121011)

  File "src\lxml\parser.pxi", line 1875, in lxml.etree._parseFilelikeDocument (src\lxml\etree.c:121294)

  File "src\lxml\parser.pxi", line 1770, in lxml.etree._parseDocFromFilelike (src\lxml\etree.c:120078)

  File "src\lxml\parser.pxi", line 1185, in lxml.etree._BaseParser._parseDocFromFilelike (src\lxml\etree.c:114806)

  File "src\lxml\parser.pxi", line 598, in lxml.etree._ParserContext._handleParseResultDoc (src\lxml\etree.c:107724)

  File "src\lxml\parser.pxi", line 709, in lxml.etree._handleParseResult (src\lxml\etree.c:109433)

  File "src\lxml\parser.pxi", line 638, in lxml.etree._raiseParseError (src\lxml\etree.c:108287)

  File "...\XRDTools\xrdtools\xrdtools\data\schemas\XRDMeasurement15.xsd", line 1
    <?xml version="1.0" encoding="UTF-8"?>
                                          ^
XMLSyntaxError: Start tag expected, '<' not found, line 1, column 1

{cd3>正在挖掘这个函数：

def validate_xrdml_schema(filename):
    """Validate the xml schema of a given file.

    Parameters
    ----------
    filename : str
        The Filename of the `.xrdml` file to test.

    Returns
    -------
    float or None
        Returns the version number as float or None if
        the file was not matching any provided xml schema.

    """
    schemas = [(1.5, 'data/schemas/XRDMeasurement15.xsd'),
               (1.4, 'data/schemas/XRDMeasurement14.xsd'),
               (1.3, 'data/schemas/XRDMeasurement13.xsd'),
               (1.2, 'data/schemas/XRDMeasurement12.xsd'),
               (1.1, 'data/schemas/XRDMeasurement11.xsd'),
               (1.0, 'data/schemas/XRDMeasurement10.xsd'),
               ]
    schemas = [(v, os.path.join(package_path, schema)) for v, schema in schemas]

    with open(filename, 'r') as f:
        data_xml = etree.parse(f)

    for version, schema in schemas:
        with open(schema, 'r') as f:
            xmlschema_doc = etree.parse(f)
            xmlschema = etree.XMLSchema(xmlschema_doc)

        valid = xmlschema.validate(data_xml)
        if valid:
            return version
    return None

据我所知，xmlschema_doc = etree.parse(f)是问题的根源。如果我将这行改为etree.parse(filename)，它将运行而不会出错，但我不确定这是否重要。除了Jupyter笔记本中的一个独立的小单元之外，我还无法将该修复应用于其他任何东西。在

是什么导致了错误？有没有一种方法可以修复python3的问题？实现该修复的最佳方法是什么？在

希望能解决这个问题。蒂娅！在

我能找到的最相关的问题是： Python 3.4 lxml.etree: Start tag expected, '<' not found, line 1, column 1

Answer 1

尝试：

with io.open(filename, 'r', encoding='utf8') as f:
    data_xml = etree.parse(f)

（io.open，因为它对python2和python3都是相同的调用）。在