从已解析的XML树中删除元素会中断迭代

从已解析的XML树中删除元素会中断迭代

问题是您要从要迭代的对象中删除元素，当删除元素时，其余元素会发生移动，因此最终可能会删除不正确的元素：

一个简单的解决方案是遍历树的副本或使用 reversed ：

复制：

 def processGroup(group):    # creates a shallow copy so we are removing from the original    # but iterating over a copy.     for e in group[:]:        if e.tag != 'a': group.remove(e) showGroup(group,'removed <' + e.tag + '>')

反转：

def processGroup(group):    # starts at the end, as the container shrinks.    # when an element is removed, we still see    # elements at the same position when we started out loop.    for e in reversed(group):        if e.tag != 'a': group.remove(e) showGroup(group,'removed <' + e.tag + '>')

使用复制逻辑：

In [7]: tree = ET.parse('test.xml')In [8]: root = tree.getroot()In [9]: for group in root:   ...:         processGroup(group)   ...:     removed <b>  len=2<group>   <a>   <c></group>removed <c>  len=1<group>   <a></group>

您也可以使用

ET.tostring

for循环代替：

import xml.etree.ElementTree as ETdef show_group(group,s):    print(s + '  len=' + str(len(group)))    print(ET.tostring(group))def process_group(group):    for e in group[:]:        if e.tag != 'a': group.remove(e) show_group(group, 'removed <' + e.tag + '>')tree = ET.parse('test.xml')root = tree.getroot()for group in root.findall(".//group"):    process_group(group)