我想知道为什么在这段代码中,
append()
看起来可以从循环内部工作,但结果xml只显示最后一次迭代的修改,而 remove()
则按预期工作。这是一个过于简化的例子,我正在处理大量数据块,并需要将相同的子树附加到许多不同的父级。from lxml import etree
xml = etree.fromstring('<tree><fruit id="1"></fruit><fruit id="2"></fruit></tree>')
sub = etree.fromstring('<apple/>')
for i, item in enumerate(xml):
item.append(sub)
print('Fruit {} with sub appended: {}'.format(
i, etree.tostring(item).decode('ascii')))
print('\nResulting tree after iterating through items with append():\n' +
etree.tostring(xml, pretty_print=True).decode('ascii'))
for item in xml:
xml.remove(item)
print('Resulting tree after iterating through items with remove():\n' +
etree.tostring(xml, pretty_print=True).decode('ascii'))
当前输出:
Fruit 0 with sub appended: <fruit id="1"><apple/></fruit>
Fruit 1 with sub appended: <fruit id="2"><apple/></fruit>
Resulting tree after iterating through items with append():
<tree>
<fruit id="1"/>
<fruit id="2">
<apple/>
</fruit>
</tree>
Resulting tree after iterating through items with remove():
<tree/>
使用append()
迭代后的期望输出结果为:
<tree>
<fruit id="1"/>
<apple/>
</fruit>
<fruit id="2">
<apple/>
</fruit>
</tree>