如何使用Python根据条件查找和删除XML文件中的元素（带有命名空间）

Question

我有一个XML文件，我想根据条件从中删除元素。但是，XML文件的名称空间由于某些不清楚的原因不允许我执行所描述的过程：1、2、3、4和5。你知道吗

我的XML如下所示：

    <?xml version='1.0' encoding='UTF-8'?>
        <PcGts xmlns="http://schema.primaresearch.org/PAGE/gts/pagecontent/2013-07-15" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://schema.primaresearch.org/PAGE/gts/pagecontent/2013-07-15 http://schema.primaresearch.org/PAGE/gts/pagecontent/2013-07-15/pagecontent.xsd">
            <Page imageFilename="1.png">
                <TextRegion custom="a">
                    <TextLine custom="readingOrder {index:0;}" id="Ar0010001l1">
                        <TextEquiv>
                            <Unicode> abc </Unicode>
                        </TextEquiv>
                    </TextLine>
                    <TextLine custom="readingOrder {index:1;}" id="Ad0010100l2">
                        <TextEquiv>
                            <Unicode />
                        </TextEquiv>
                </TextRegion>
            </Page>
        </PcGts>

我的目标是清除“Unicode”标记中没有文本的所有TextLine节点。因此输出将是：

    <?xml version='1.0' encoding='UTF-8'?>
        <PcGts xmlns="http://schema.primaresearch.org/PAGE/gts/pagecontent/2013-07-15" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://schema.primaresearch.org/PAGE/gts/pagecontent/2013-07-15 http://schema.primaresearch.org/PAGE/gts/pagecontent/2013-07-15/pagecontent.xsd">
            <Page imageFilename="1.png">
                <TextRegion custom="a">
                    <TextLine custom="readingOrder {index:0;}" id="Ar0010001l1">
                        <TextEquiv>
                            <Unicode> abc </Unicode>
                        </TextEquiv>
                    </TextLine>
                </TextRegion>
            </Page>
        </PcGts>

我尝试使用上面链接中的一些建议。 但是：

 import lxml.etree as ET
 data = ET.parse(file)
 root = data.getroot()
 for x in root.xpath("//Unicode"):
     print(x.text)

没有找到任何标签。 再来一次：

for x in root.xpath("//{http://schema.primaresearch.org/PAGE/gts/pagecontent/2013-07-15}Unicode"):
   print(x.text)

抛出“xpathevaleror:无效表达式”

那么，从这个XML文件中删除Unicode标记为空的所有节点的最简单方法是什么（以及如何找到它们？）？你知道吗

谢谢。你知道吗

Answer 1

首先，您的xml缺少<TextLine custom="readingOrder {index:1;}" id="Ad0010100l2">的结束标记，但是如果您将其插入适当的位置，那么以下内容应该可以帮助您：

my_xml = """[your xml above, corrected]"""
data = ET.XML(my_xml.encode('ascii'))
for target in data.xpath("//*[local-name() = 'Unicode'][not(text())]"):
    target.getparent().remove(target)     

print(etree.tostring(data,  xml_declaration=True))

输出：

    <?xml version=\'1.0\' encoding=\'ASCII\'?>\n
<PcGts
    xmlns="http://schema.primaresearch.org/PAGE/gts/pagecontent/2013-07-15"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://schema.primaresearch.org/PAGE/gts/pagecontent/2013-07-15 http://schema.primaresearch.org/PAGE/gts/pagecontent/2013-07-15/pagecontent.xsd">
    <Page imageFilename="1.png">
        <TextRegion custom="a">
            <TextLine custom="readingOrder {index:0;}" id="Ar0010001l1">
                <TextEquiv>
                    <Unicode> abc </Unicode>
                </TextEquiv>
            </TextLine>
            <TextLine custom="readingOrder {index:1;}" id="Ad0010100l2">
                <TextEquiv/>
            </TextLine>
        </TextRegion>
    </Page>
</PcGts>  

Answer 2

我终于找到了解决问题的办法。你知道吗

import lxml.etree as ET
my_xml = """...xml content..."""
data = ET.XML(my_xml.encode('UTF-8'))

#this loop remove "<Unicode />" tags.
for target in data.xpath("//*[local-name() = 'Unicode'][not(text())]"):
    target.getparent().remove(target)  

#and this loop remove nodes without children like "<TextEquiv><Unicode /></TextEquiv>" 
#(after the removing of "<Unicode />")
for el in data.iter():
    if len(list(el.iterchildren())) or ''.join([_.strip() for _ in el.itertext()]):
        pass
    else:
        parent = el.getparent()
        if parent is not None:
            parent.remove(el)
#and this loop remove nodes without children again, but now - it's "<TextLine>" tag
for el in data.iter():
    if len(list(el.iterchildren())) or ''.join([_.strip() for _ in el.itertext()]):
        pass
    else:
        parent = el.getparent()
        if parent is not None:
            parent.remove(el)

print(ET.tostring(data,  xml_declaration=True))

这个想法来自Remove xml nodes without child nodes using python