如何使用 Python 从 XML 中删除元素
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How to remove elements from XML using Python
提问by dwich
I got stuck with XML and Python. The task is simple but I couldn't resolve it so far and spent on that long time. I came here for an advice how to solve it with couple of lines.
我被 XML 和 Python 困住了。任务很简单，但到目前为止我无法解决它并花了很长时间。我来这里是为了建议如何用几行来解决它。
Thanks for any help with traversing the tree. I always ended up with too many or too few elements. Elements can be nested without limit. Given example is just an example. I will accept any solution, not picky about dom, minidom, sax, whatever..
感谢您对遍历树的任何帮助。我总是以太多或太少的元素结束。元素可以无限制地嵌套。给出的例子只是一个例子。我会接受任何解决方案，不挑剔 dom、minidom、sax 等等。
I have an XML file similar to this one:
我有一个类似于这个的 XML 文件：
<root>
<elm>
<elm>Common content</elm>
<elm xmlns="http://example.org/ns">
<elm lang="en">Content EN</elm>
<elm lang="cs">?lu?ou?ky koní?ek</elm>
</elm>
<elm xml:id="abc123">Common content</elm>
<elm lang="en">Content EN</elm>
<elm lang="cs">Content CS</elm>
<elm lang="en">
<elm>Content EN</elm>
<elm>Content EN</elm>
</elm>
<elm lang="cs">
<elm>Content CS</elm>
<elm>Content CS</elm>
</elm>
</elm>
</root>
What I need - parse the XML and write a new file. The new file should contain all the elements for given language and elements without langattribute.
我需要什么 - 解析 XML 并编写一个新文件。新文件应该包含给定语言的所有元素和没有lang属性的元素。
For "cs" language the output file should containt this:
对于“cs”语言，输出文件应包含：
<root>
<elm>
<elm>Common content</elm>
<elm xmlns="http://example.org/ns">
<elm lang="cs">?lu?ou?ky koní?ek</elm>
</elm>
<elm xml:id="abc123">Common content</elm>
<elm lang="cs">Content CS</elm>
<elm lang="cs">
<elm>Content CS</elm>
<elm>Content CS</elm>
</elm>
</elm>
</root>
If you can make it to omit the langattribute in the new file, even better. But it's not that important.
如果你能让它省略lang新文件中的属性，那就更好了。但这并不重要。
UPDATE1:Added unicode characters and namespace attribute.
UPDATE1：添加了 unicode 字符和命名空间属性。
UPDATE2:Using Python 2.5, standard libraries preferred.
UPDATE2：使用 Python 2.5，首选标准库。
采纳答案by unutbu
Using lxml:
使用lxml：
import lxml.etree as le
with open('doc.xml','r') as f:
doc=le.parse(f)
for elem in doc.xpath('//*[attribute::lang]'):
if elem.attrib['lang']=='en':
elem.attrib.pop('lang')
else:
parent=elem.getparent()
parent.remove(elem)
print(le.tostring(doc))
yields
产量
<root>
<elm>Common content</elm>
<elm>
<elm>Content EN</elm>
</elm>
<elm>Common content</elm>
<elm>Content EN</elm>
<elm>
<elm>Content EN</elm>
<elm>Content EN</elm>
</elm>
</root>
回答by Alex Martelli
I'm not sure how best to remove the langattribute, but here's some code that does the other changes (Python 2.7; for 2.5 or 2.6, use getIteratorinstead of iter), assuming that when you remove an element you also always want to remove everything contained in that element.
我不确定如何最好地删除该lang属性，但这里有一些代码可以进行其他更改（Python 2.7；对于 2.5 或 2.6，使用getIterator代替iter），假设当您删除一个元素时，您也总是想删除包含的所有内容在那个元素中。
This code just prints the result to standard output (you could redirect it as you wish, of course, or directly write it to some new file, and so on):
这段代码只是将结果打印到标准输出（当然，您可以根据需要重定向它，或者直接将其写入某个新文件，等等）：
import sys
from xml.etree import cElementTree as et
def picklang(path, lang='en'):
tr = et.parse(path)
for element in tr.iter():
for subelement in element:
la = subelement.get('lang')
if la is not None and la != lang:
element.remove(subelement)
return tr
if __name__ == '__main__':
tr = picklang('la.xml')
tr.write(sys.stdout)
print
With la.xmlbeing your example, this writes
随着la.xml是你的榜样，这写
<root>
<elm>Common content</elm>
<elm>
<elm lang="en">Content EN</elm>
</elm>
<elm>Common content</elm>
<elm lang="en">Content EN</elm>
<elm lang="en">
<elm>Content EN</elm>
<elm>Content EN</elm>
</elm>
</root>
回答by bhuvi
updating @Alex Martelli's code to remove a bug where the element list is updated in place. Above solution will give wrong answer if the input is little more complex.
更新@Alex Martelli 的代码以删除元素列表就地更新的错误。如果输入稍微复杂一点，上述解决方案将给出错误的答案。
import sys
from xml.etree import cElementTree as et
def picklang(path, lang='en'):
tr = et.parse(path)
for element in tr.iter():
for subelement in element[:]:
la = subelement.get('lang')
if la is not None and la != lang:
element.remove(subelement)
return tr
if __name__ == '__main__':
tr = picklang('la.xml')
tr.write(sys.stdout)
print
Code in line 7 for subelement in element:is changed to for subelement in element[:]:as it is incorrect to update list in place while iterating over it.
第 7 行中的代码for subelement in element:更改为，for subelement in element[:]:因为在迭代列表时就地更新列表是不正确的。
This code iterates over a copy of element list and removes elements when lang != "en" in the original element list.
此代码迭代元素列表的副本，并在原始元素列表中 lang != "en" 时删除元素。
