目标是读取维基百科转储(70Gb 文件)中的所有内容。这是不可能加载到内存中的，因此我尝试增量解析文件并从中获取一些值。然而，我刚刚编写的脚本没有打印任何内容，并且立即占用了我所有的内存。
这是代码:
from lxml import etree
def fast_iter(context, func, *args, **kwargs):
for event, elem in context:
func(elem, *args, **kwargs)
elem.clear()
for ancestor in elem.xpath('ancestor-or-self::*'):
while ancestor.getprevious() is not None:
del ancestor.getparent()[0]
del context
def process_element(elem):
#print(elem)
print (elem.xpath( './revision/text/text( )' ))
context = etree.iterparse( 'enwiki-latest-pages-articles-multistream.xml', tag='page' )
fast_iter(context,process_element)
当此脚本应用于小型 xml 文件时，它会打印请求的 xpath 中的值。
但是，当应用于完整文件时，什么也没有发生。
这是来自维基百科转储的相同行
<mediawiki xmlns="http://www.mediawiki.org/xml/export-0.10/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.mediawiki.org/xml/export-0.10/ http://www.mediawiki.org/xml/export-0.10.xsd" version="0.10" xml:lang="en">
<siteinfo>
<sitename>Wikipedia</sitename>
<dbname>enwiki</dbname>
<base>https://en.wikipedia.org/wiki/Main_Page</base>
<generator>MediaWiki 1.33.0-wmf.19</generator>
<case>first-letter</case>
<namespaces>
<namespace key="-2" case="first-letter">Media</namespace>
<namespace key="-1" case="first-letter">Special</namespace>
<namespace key="0" case="first-letter" />
<namespace key="1" case="first-letter">Talk</namespace>
<namespace key="2" case="first-letter">User</namespace>
<namespace key="3" case="first-letter">User talk</namespace>
<namespace key="4" case="first-letter">Wikipedia</namespace>
<namespace key="5" case="first-letter">Wikipedia talk</namespace>
<namespace key="6" case="first-letter">File</namespace>
<namespace key="7" case="first-letter">File talk</namespace>
<namespace key="8" case="first-letter">MediaWiki</namespace>
<namespace key="9" case="first-letter">MediaWiki talk</namespace>
<namespace key="10" case="first-letter">Template</namespace>
<namespace key="11" case="first-letter">Template talk</namespace>
<namespace key="12" case="first-letter">Help</namespace>
<namespace key="13" case="first-letter">Help talk</namespace>
<namespace key="14" case="first-letter">Category</namespace>
<namespace key="15" case="first-letter">Category talk</namespace>
<namespace key="100" case="first-letter">Portal</namespace>
<namespace key="101" case="first-letter">Portal talk</namespace>
<namespace key="108" case="first-letter">Book</namespace>
<namespace key="109" case="first-letter">Book talk</namespace>
<namespace key="118" case="first-letter">Draft</namespace>
<namespace key="119" case="first-letter">Draft talk</namespace>
<namespace key="446" case="first-letter">Education Program</namespace>
<namespace key="447" case="first-letter">Education Program talk</namespace>
<namespace key="710" case="first-letter">TimedText</namespace>
<namespace key="711" case="first-letter">TimedText talk</namespace>
<namespace key="828" case="first-letter">Module</namespace>
<namespace key="829" case="first-letter">Module talk</namespace>
<namespace key="2300" case="first-letter">Gadget</namespace>
<namespace key="2301" case="first-letter">Gadget talk</namespace>
<namespace key="2302" case="case-sensitive">Gadget definition</namespace>
<namespace key="2303" case="case-sensitive">Gadget definition talk</namespace>
</namespaces>
</siteinfo>
<page>
<title>AccessibleComputing</title>
<ns>0</ns>
<id>10</id>
<redirect title="Computer accessibility" />
<revision>
<id>854851586</id>
<parentid>834079434</parentid>
<timestamp>2018-08-14T06:47:24Z</timestamp>
<contributor>
<username>Godsy</username>
<id>23257138</id>
</contributor>
<comment>remove from category for seeking instructions on rcats</comment>
<model>wikitext</model>
<format>text/x-wiki</format>
<text xml:space="preserve">#REDIRECT [[Computer accessibility]]
{{R from move}}
{{R from CamelCase}}
{{R unprintworthy}}</text>
<sha1>42l0cvblwtb4nnupxm6wo000d27t6kf</sha1>
</revision>
</page>
<page>
<title>Anarchism</title>
<ns>0</ns>
<id>12</id>
<revision>
<id>885648527</id>
<parentid>885645378</parentid>
<timestamp>2019-03-01T11:16:23Z</timestamp>
<contributor>
<username>Jarnsax</username>
<id>33627956</id>
</contributor>
<comment>improve citation metadata</comment>
<model>wikitext</model>
<format>text/x-wiki</format>
<text xml:space="preserve">{{redirect2|Anarchist|Anarchists|the fictional character|Anarchist (comics)|other uses|Anarchists (disambiguation)}}
{{pp-move-indef}}
{{short description|Political philosophy that advocates self-governed societies}}
{{Use dmy dates|date=July 2018}}
{{use British English|date=January 2014}}
{{Anarchism sidebar}}
{{Basic forms of government}}
'''Anarchism''' is an [[anti-authoritarian]] [[political philosophy]]{{sfn|McLaughlin|2007|p=59}}{{sfn|Flint|2009|p=27}} that advocates [[Self-governance|self-governed]] societies based on voluntary, [[cooperative]] institutions and the rejection of coercive [[Hierarchy|hierarchies]] those societies view as unjust. These institutions are often described as [[Stateless society|stateless societies]],{{r|group=note|Note01}}{{sfn|Sheehan|2003|p=85}} although several authors have defined them more specifically as distinct institutions based on non-hierarchical or [[Free association (communism and anarchism)|free associations]].{{r|group=note|Note02}} Anarchism holds the [[State (polity)|state]] to be undesirable, unnecessary, and harmful.{{r|group=note|Note03}}<ref name=definition /> Any philosophy consistent with statelessness, that is, principled opposition to the State, is anarchist, thus anarchist schools of thought range from [[anarcho-communism]] to [[anarcho-capitalism]].{{sfn|Fiala|2018}}
While [[Anti-statism|opposition to the state]] is central,{{r|group=note|Note04}} many forms of anarchism specifically entail opposing authority or hierarchical organisation based on authority in the conduct of all human relations.{{r|group=note|Note05}} Anarchism is often considered a [[Far-left politics|far-left]] ideology,{{r|group=note|Note06}}{{sfn|Kahn|2000}}{{sfn|Moyihan|2007}} and much of [[anarchist economics]] and [[Anarchist law|anarchist legal philosophy]] reflect [[Libertarian socialism|anti-authoritarian interpretations]] of [[Anarcho-communism|communism]], [[Collectivist anarchism|collectivism]], [[Anarcho-syndicalism|syndicalism]], [[Mutualism (economic theory)|mutualism]], or [[participatory economics]].{{r|group=note|Note07}}
Anarchism does not offer a fixed body of doctrine from a single particular world view, instead fluxing and flowing as a philosophy.{{sfn|Marshall|2010|p=16}} Many types and traditions of anarchism exist, not all of which are mutually exclusive.{{sfn|Sylvan|2007|p=262}} [[Anarchist schools of thought]] can differ fundamentally, supporting anything from extreme [[individualism]] to complete [[collectivism]].{{sfn|McLean|McMillan|2003|loc= Anarchism}} Strains of anarchism have often been divided into the categories of [[Social anarchism|social]] and [[individualist anarchism]] or similar dual classifications.{{sfn|Ostergaard|p=14|loc=Anarchism}}{{sfn|Kropotkin|2002|p=5}}{{sfn|Fowler|1972}}
</text>
</revision>
</page>
</mediawiki>
以前有人这样做过吗？知道如何有效解析这个巨大的转储吗？是否有任何包/lib 之前已经做到了？我不想重新发明轮子。
最佳答案
Question: Parsing incrementally a large wikipedia dump XML file
When this (the Questions) script is applied in a small xml file, it prints the values from the requested xpath.
However when applied on the full file, nothing happens.
我想知道，您可以从小文件中获得任何内容，因为您不使用命名空间参数。
Wikipedia xml 文件使用以下默认命名空间:
<mediawiki xmlns="http://www.mediawiki.org/xml/export-0.10/"
此示例使用lxml:
from lxml import etree
class Wikipedia:
def __init__(self, fh, tag):
"""
Initialize 'iterparse' to only generate 'end' events on tag '<entity>'
:param fh: File Handle from the XML File to parse
:param tag: The tag to process
"""
# Prepend the default Namespace {*} to get anything.
self.context = etree.iterparse(fh, events=("end",), tag=['{*}' + tag])
def _parse(self):
"""
Parse the XML File for all '<tag>...</tag>' Elements
Clear/Delete the Element Tree after processing
:return: Yield the current 'Event, Element Tree'
"""
for event, elem in self.context:
yield event, elem
elem.clear()
while elem.getprevious() is not None:
del elem.getparent()[0]
def __iter__(self):
"""
Iterate all '<tag>...</tag>' Element Trees yielded from self._parse()
:return: Dict var 'entity' {tag1, value, tag2, value, ... ,tagn, value}}
"""
for event, elem in self._parse():
entity = {}
# Assign the 'elem.namespace' to the 'xpath'
entity['revision'] = elem.xpath('./xmlns:revision/xmlns:text/text( )',
namespaces={'xmlns':etree.QName(elem).namespace})
yield entity
if __name__ == "__main__":
XML = b""""""<?xml version='1.0' encoding='UTF-8'?>
<mediawiki xmlns="http://www.mediawiki.org/xml/export-0.10/"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.mediawiki.org/xml/export-0.10/
http://www.mediawiki.org/xml/export-0.10.xsd"
version="0.10" xml:lang="en">
<siteinfo>
<sitename>Wikipedia</sitename>
<dbname>enwiki</dbname>
... (omitted for brevity)""""""
#with open('.\\FILE.XML', 'rb') as in_xml_
with io.BytesIO(XML) as in_xml:
for record in Wikipedia(in_xml, tag='page'):
print("record:{}".format(record))
Output:
record:{'revision': ['#REDIRECT [[Computer accessi... (omitted for brevity) record:{'revision': ["{{redirect2|Anarchist|Anarch... (omitted for brevity)
使用 Python 测试:3.5 - lxml.etree:3.7.1
关于python - 使用 python 增量解析大型维基百科转储 XML 文件，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/55137013/