我有一个非常大的.xml文件,我正在尝试制作一个新的.xml文件,该文件只占这个较大文件内容的一小部分.我想指定一个属性(在我的例子中,是一个itemID)并给它一些特定的值然后它将除去那些具有那些itemID及其子元素的元素.
我的大.xml文件看起来像这样：
<?xml version='1.0' encoding='UTF-8'?>
<api version="2">
<currentTime>2013-02-27 17:00:18</currentTime>
<result>
<rowset name="assets" key="itemID" columns="itemID,locationID,typeID,quantity,flag,singleton">
<row itemID="1008551770576" locationID="31000559" typeID="17187" quantity="1" flag="0" singleton="1" rawQuantity="-1" />
<row itemID="1008700753886" locationID="31000559" typeID="17187" quantity="1" flag="0" singleton="1" rawQuantity="-1" />
<row itemID="1008700756994" locationID="31000559" typeID="17184" quantity="1" flag="0" singleton="1" rawQuantity="-1" />
<row itemID="1008701224901" locationID="31000559" typeID="17186" quantity="1" flag="0" singleton="1" rawQuantity="-1" />
<row itemID="1004072840841" locationID="31002238" typeID="17621" quantity="1" flag="0" singleton="1" rawQuantity="-1">
<rowset name="contents" key="itemID" columns="itemID,typeID,quantity,flag,singleton">
<row itemID="150571923" typeID="25863" quantity="2" flag="119" singleton="0" />
<row itemID="188435728" typeID="3388" quantity="1" flag="119" singleton="0" />
<row itemID="210122947" typeID="3419" quantity="4" flag="119" singleton="0" />
</rowset>
</row>
<row itemID="1005279202146" locationID="31002238" typeID="17621" quantity="1" flag="0" singleton="1" rawQuantity="-1">
<rowset name="contents" key="itemID" columns="itemID,typeID,quantity,flag,singleton">
<row itemID="1004239962001" typeID="16275" quantity="49596" flag="4" singleton="0" />
<row itemID="1005364142068" typeID="4246" quantity="156929" flag="4" singleton="0" />
<row itemID="1005624252854" typeID="4247" quantity="93313" flag="4" singleton="0" />
</rowset>
</row>
<row itemID="1004388226389" typeID="648" quantity="1" flag="0" singleton="1" rawQuantity="-1">
<rowset name="contents" key="itemID" columns="itemID,typeID,quantity,flag,singleton">
<row itemID="1004388228218" typeID="31119" quantity="1" flag="92" singleton="1" rawQuantity="-1" />
<row itemID="1004388701243" typeID="31119" quantity="1" flag="94" singleton="1" rawQuantity="-1" />
<row itemID="1004388701485" typeID="31119" quantity="1" flag="93" singleton="1" rawQuantity="-1" />
<row itemID="1009147502645" typeID="51" quantity="1" flag="5" singleton="1" rawQuantity="-1" />
</rowset>
</row>
</rowset>
</result>
<cachedUntil>2013-02-27 23:00:18</cachedUntil>
</api>
这个文件有大约九万行,大约是9兆字节.
请注意itemIDs和某些项目类型如何(但并不总是)内部有更多项目,这些子项目也有自己的itemID.我正在尝试获取一些特定的itemID和他们的孩子,并遗漏所有其他人.
我使用了this answer的代码,它让我非常接近.它是完美的,除了它遗漏了我使用的itemID的孩子.
我的代码看起来像这样：
import lxml.etree as le
##Take this big .xml file and pull out just the parts we want then write those to a new .xml file##
with open(filename,'r') as f:
doc=le.parse(f)
for elem in doc.xpath('//*[attribute::itemID]'):
if elem.attrib['itemID']=='1004072840841':
elem.attrib.pop('itemID')
else:
parent=elem.getparent()
parent.remove(elem)
print(le.tostring(doc))
这就是打印出来的样子：
<api version="2">
<currentTime>2013-03-01 21:46:52</currentTime>
<result>
<rowset name="assets" key="itemID" columns="itemID,locationID,typeID,quantity,flag,singleton">
<row locationID="31002238" typeID="17621" quantity="1" flag="0" singleton="1" rawQuantity="-1">
<rowset name="contents" key="itemID" columns="itemID,typeID,quantity,flag,singleton">
</rowset>
</row>
</rowset>
</result>
<cachedUntil>2013-03-02 03:46:53</cachedUntil>
</api>
我希望它看起来像这样：
<api version="2">
<currentTime>2013-03-01 21:46:52</currentTime>
<result>
<rowset name="assets" key="itemID" columns="itemID,locationID,typeID,quantity,flag,singleton">
<row locationID="31002238" typeID="17621" quantity="1" flag="0" singleton="1" rawQuantity="-1">
<rowset name="contents" key="itemID" columns="itemID,typeID,quantity,flag,singleton">
<row itemID="150571923" typeID="25863" quantity="2" flag="119" singleton="0" />
<row itemID="188435728" typeID="3388" quantity="1" flag="119" singleton="0" />
<row itemID="210122947" typeID="3419" quantity="4" flag="119" singleton="0" />
</rowset>
</row>
</rowset>
</result>
<cachedUntil>2013-03-02 03:46:53</cachedUntil>
</api>
我不能很好地理解代码,看看我需要改变什么,以便还包括我搜索的itemID的子代.此外,理想情况下,我可以放入多个itemID,除了那些itemID和他们的孩子之外,它将除去所有项目ID.这意味着它需要保留itemID = [number]行属性(这样当我使用这个xml文件时,我可以使用xPath来引用特定的itemID及其子项.)
所以我的主要问题是如何在我生成的.xml中包含我搜索的itemID的子项.我的第二个问题是关于如何同时为多个itemID执行此操作(以便生成的.xml文件将除去那些itemID及其子项之外的所有内容.)
更新：UGLY SOLUTION
我发现elem.attrib.pop(‘itemID’)部分是取出itemID的部分,因为我想有多个项目ID并且他们的孩子仍然需要保留这个,所以我把那个部分拿出去了.我试图找到一种方法来跳过我正在搜索的itemID的行的子项,我想出的是用一个属性标记每个,然后我可以搜索并删除所有不有那个属性.我不需要我正在做的标志属性所以我继续使用它来实现这个目的(因为尝试引入一个新属性时遇到了一个关键错误,当我尝试迭代它们时.)只是标记孩子们还不够,我还要标记孩子们的孩子.
这是我丑陋的解决方案：
with open(filename,'r') as f:
doc=le.parse(f)
for elem in doc.xpath('//*[attribute::itemID]'):
if elem.attrib['itemID']=='1004072840841' or elem.attrib['itemID']=='1005279202146': # this or statement lets me get a resulting .xml file that has two itemIDs and their children
elem.attrib['flag']='Keep'
for child in elem.iterchildren():
child.attrib['flag']='Keep'
for c in child.iterchildren():
c.attrib['flag']='Keep'
else:
pass
for e in doc.xpath('//*[attribute::flag]'):
if e.attrib['flag']!='Keep':
parent=e.getparent()
parent.remove(e)
else:
pass
print(le.tostring(doc))
##This part writes the pruned down .xml to a file##
with open('test.xml', 'w') as t:
for line in le.tostring(doc):
t.write(line)
t.close
这个丑陋的解决方案涉及大量迭代数据,我怀疑,远非最有效的方法来完成这项工作,但它确实有效.
解决方法:
目前还不是很清楚你所追求的是什么,但这段代码会产生你说你想要的输出：
from lxml import etree as ET
def filter_by_itemid(doc, idlist):
rowset = doc.xpath("/api/result/rowset[@name='assets']")[0]
for elem in rowset.getchildren():
if int(elem.get("itemID")) not in idlist:
rowset.remove(elem)
return doc
doc = ET.parse("test.xml")
filter_by_itemid(doc, [1004072840841])
print(ET.tostring(doc))