我通过他们的API从Flickr中提取图像数据，我得到的是几千个xml对象，如下所示：
<photo accuracy="15" context="0" dateupload="1398279194" farm="8" geo_is_contact="0" geo_is_family="0" geo_is_friend="0" geo_is_public="1" height_n="320" id="13986079375" isfamily="0" isfriend="0" ispublic="1" latitude="41.828482" license="0" longitude="-87.624506" owner="100231432@N02" pathalias="perspectivesschools" place_id="cF8n.mJTWrhYf0uBEw" secret="f46eef0b1d" server="7308" title="Sean Gallagher, Pulitzer Photojournalist visits MSA" url_n="https://farm8.staticflickr.com/7308/13986079375_f46eef0b1d_n.jpg" width_n="213" woeid="28297331" />
<photo accuracy="12" context="0" dateupload="1394558054" farm="4" geo_is_contact="0" geo_is_family="0" geo_is_friend="0" geo_is_public="1" height_n="213" id="13086071753" isfamily="0" isfriend="0" ispublic="1" latitude="51.451914" license="2" longitude="-0.122882" owner="96189004@N04" pathalias="" place_id="JYdWRftQUbMvFA" secret="265103ac38" server="3040" title="" url_n="https://farm4.staticflickr.com/3040/13086071753_265103ac38_n.jpg" width_n="320" woeid="13978" />
<photo accuracy="12" context="0" dateupload="1394558019" farm="8" geo_is_contact="0" geo_is_family="0" geo_is_friend="0" geo_is_public="1" height_n="213" id="13086343854" isfamily="0" isfriend="0" ispublic="1" latitude="51.451914" license="2" longitude="-0.122882" owner="96189004@N04" pathalias="" place_id="JYdWRftQUbMvFA" secret="a6858f84d2" server="7451" title="" url_n="https://farm8.staticflickr.com/7451/13086343854_a6858f84d2_n.jpg" width_n="320" woeid="13978" />
现在我想在一次运行中提取属性'lat'和'long'的数据。而另一个属性'url_n'的数据。我怎么能用Python做到这一点？我没有解析xml数据的经验，也不知道从哪里开始。
非常感谢！
答案 0 :(得分：1)
使用正则表达式解析XML是not a good idea。尝试BeautifulSoup - 它不仅解析XML，而且还有一些函数可以轻松地获取与所选内容及其属性相关的下一个/ parent / etc元素。
使用示例：
from bs4 import BeautifulSoup
(...)
soup = BeautifulSoup(flickr_xml)
for photo in soup.find_all('photo'):
print(photo.get('url_n'))
答案 1 :(得分：1)
虽然Python中有多个与XML相关的包，但包括。 stdlib一，我更喜欢使用lxml
它提供了我所需要的一切（良好的XPath支持，模式验证等），我更喜欢保留数字
我用的小包装。
对于Flickr的xml文档，解决方案看起来像
flickr.py from lxml import etree
xmllines = """
<photo accuracy="15" context="0" dateupload="1398279194" farm="8" geo_is_contact="0" geo_is_family="0" geo_is_friend="0" geo_is_public="1" height_n="320" id="13986079375" isfamily="0" isfriend="0" ispublic="1" latitude="41.828482" license="0" longitude="-87.624506" owner="100231432@N02" pathalias="perspectivesschools" place_id="cF8n.mJTWrhYf0uBEw" secret="f46eef0b1d" server="7308" title="Sean Gallagher, Pulitzer Photojournalist visits MSA" url_n="https://farm8.staticflickr.com/7308/13986079375_f46eef0b1d_n.jpg" width_n="213" woeid="28297331" />
<photo accuracy="12" context="0" dateupload="1394558054" farm="4" geo_is_contact="0" geo_is_family="0" geo_is_friend="0" geo_is_public="1" height_n="213" id="13086071753" isfamily="0" isfriend="0" ispublic="1" latitude="51.451914" license="2" longitude="-0.122882" owner="96189004@N04" pathalias="" place_id="JYdWRftQUbMvFA" secret="265103ac38" server="3040" title="" url_n="https://farm4.staticflickr.com/3040/13086071753_265103ac38_n.jpg" width_n="320" woeid="13978" />
<photo accuracy="12" context="0" dateupload="1394558019" farm="8" geo_is_contact="0" geo_is_family="0" geo_is_friend="0" geo_is_public="1" height_n="213" id="13086343854" isfamily="0" isfriend="0" ispublic="1" latitude="51.451914" license="2" longitude="-0.122882" owner="96189004@N04" pathalias="" place_id="JYdWRftQUbMvFA" secret="a6858f84d2" server="7451" title="" url_n="https://farm8.staticflickr.com/7451/13086343854_a6858f84d2_n.jpg" width_n="320" woeid="13978" />
"""
for line in xmllines.strip().splitlines():
doc = etree.fromstring(line)
urls = doc.xpath("/photo/@url_n")
if urls:
url = urls[0]
print url
else:
print "---no attribute url_n was found---"
将输出：
$ python flickr.py
https://farm8.staticflickr.com/7308/13986079375_f46eef0b1d_n.jpg
https://farm4.staticflickr.com/3040/13086071753_265103ac38_n.jpg
https://farm8.staticflickr.com/7451/13086343854_a6858f84d2_n.jpg