使用Python LXML从XML读取元素值

Question

<markets xmlns="http://www.eoddsmaker.net/schemas/markets/1.0" D="2015-03-23T23:12:34" CNT="1521">
 <S I="50" N="Football">
  <C I="65" N="Russia">
    <L I="167" N="Premier League">
      <E I="1049367" DT="2015-04-05T15:00:00" ISH="0" BKS="20" T1="Ufa" T2="Terek Groznyi" T1I="79698" T2I="44081">
        <M K="1x2">
          <B I="81" BTDT="2015-03-23T23:04:00,825">
            <O N="1" V="3"/>
            <O N="X" V="3.1"/>
            <O N="2" V="2.25"/>
        </B>
      </M>
     </E>
    </L>
   </C>
 </S>
</markets>

我正在尝试使用Python中的etree来解析这个XML。我以前做过XML解析，但是文档总是采用这种格式。

  <tag> value </tag>

我不确定如何将"D“与"Markets”以及所有其他值区分开来。

这是我打开和解析XML文档的方式：

z = gzip.open("code2.zip", "r")

tree = etree.parse(z)
print(etree.tostring(tree, pretty_print=True))

我试过了：

for markets in tree.findall('markets'):
    print "found"

然而，这并不起作用。我希望能得到一些建议/建议。希望一旦我得到第一个"D“提取，我将能够得到其余的。

Answer 1

这是处理具有默认名称空间的XML时的常见错误。您的XML具有默认名称空间，即在此处声明的没有前缀的名称空间：

xmlns="http://www.eoddsmaker.net/schemas/markets/1.0“

因此，在您的示例中，所有元素都隐式地考虑在该名称空间中。使用xpath()查询名称空间中的元素的一种可能方法是：

.......
#creating prefix-to-namespace_uri mapping
ns = {'d' : 'http://www.eoddsmaker.net/schemas/markets/1.0'}

#use registered prefix along with the element name to query, and pass the mapping as 2nd argument
markets = tree.xpath('//d:markets', namespaces=ns)[0]

#get and print value of D attribute from <markets> :
print markets.get('D')

Answer 2

我在不了解etree的情况下回答这个问题。我只需打开以下页面：https://docs.python.org/2/library/xml.etree.elementtree.html#parsing-xml

您正在寻找的是属性，并且展示了如何非常清晰地派生它们：

tree = etree.parse(z)
root = tree.getroot()
print root.attrib

这里有<markets>元素的所有属性，比如D和CNT。

你应该能够自己解决剩下的问题。您只需遍历每个元素的子元素并从每个元素中获取.attrib。

考虑到我很容易找到这个答案，请在发布问题之前做更多的研究:)

附注:这个答案是为Python 2.7编写的。对于Python3，它将是print(tree.attrib)

Answer 3

在xml.etree上试试这个

import xml.etree.ElementTree as ET
root = ET.fromstring("""<markets xmlns="http://www.eoddsmaker.net/schemas/markets/1.0" D="2015-03-23T23:12:34" CNT="1521">
     <S I="50" N="Football">
      <C I="65" N="Russia">
        <L I="167" N="Premier League">
          <E I="1049367" DT="2015-04-05T15:00:00" ISH="0" BKS="20" T1="Ufa" T2="Terek Groznyi" T1I="79698" T2I="44081">
            <M K="1x2">
              <B I="81" BTDT="2015-03-23T23:04:00,825">
                <O N="1" V="3"/>
                <O N="X" V="3.1"/>
                <O N="2" V="2.25"/>
            </B>
          </M>
         </E>
        </L>
       </C>
     </S>
    </markets>""")

>>>print root.attrib
{'CNT': '1521', 'D': '2015-03-23T23:12:34'}
>>>print root[0].attrib
{'I': '50', 'N': 'Football'}
#and so on to next parse next line

如果需要从 xml 文件进行解析，则使用。

import xml.etree.ElementTree as ET
tree = ET.parse('file.xml')
root = tree.getroot()

有关更多信息，请参阅https://docs.python.org/2/library/xml.etree.elementtree.html