LXML，如何獲取多組屬性到列表

Question

我有類似的問題：

如何使用XPath在XML文檔中選擇多組屬性？

我的XML數據如下所示：

<?xml version="1.0" encoding="utf-8"?>
<Basic>
    <Segment>
        <Sample value="12" data2="25" data3="23"/>
        <Sample value="13" data2="0" data3="323"/>
        <Sample value="14" data2="2" data3="3"/>
    </Segment>
</Basic>

什么是將這些datax值提供給列表的最簡單的python方法。

例如： data2 = ['25','0','2']

Answer 1

使用xpath：

from lxml import etree
from collections import defaultdict
from pprint import pprint

doc="""<?xml version="1.0" encoding="utf-8"?>
<Basic>
    <Segment>
        <Sample value="12" data2="25" data3="23"/>
        <Sample value="13" data2="0" data3="323"/>
        <Sample value="14" data2="2" data3="3"/>
    </Segment>
</Basic>
"""
el = etree.fromstring(doc)
data2 = el.xpath('//@data2')
dataX = el.xpath('//@*[starts-with(name(), "data")]')
print data2
print dataX

# With iteration over Sample elements, like in J.F. Sebastian answer, but with XPath
d = defaultdict(list)
for sample in el.xpath('//Sample'):
    for attr_name, attr_value in sample.items():
        d[attr_name].append(attr_value)

pprint(dict(d))

輸出：

['25', '0', '2']
['25', '23', '0', '323', '2', '3']
{'data2': ['25', '0', '2'],
 'data3': ['23', '323', '3'],
 'value': ['12', '13', '14']}

Answer 2

獲取屬性值的最簡單方法是使用etree.Element.get （' attr_name '）：

from lxml import etree

s = '''<?xml version="1.0" encoding="utf-8"?>
<Basic>
    <Segment>
        <Sample value="12" data2="25" data3="23"/>
        <Sample value="13" data2="0" data3="323"/>
        <Sample value="14" data2="2" data3="3"/>
    </Segment>
</Basic>'''

# ❗️for python2
# tree = etree.fromstring(s)

# ❗️for python3
tree = etree.fromstring(s.encode("utf-8"))

samples = tree.xpath('//Sample')

print([sample.get('data2') for sample in samples])
>>> ['25', '0', '2']

Answer 3

使用stdlib中的cElementTree ：

import sys
from collections import defaultdict
from xml.etree import cElementTree as etree

d = defaultdict(list)
for ev, el in etree.iterparse(sys.stdin):
    if el.tag == 'Sample':
       for name in "value data2 data3".split():
           d[name].append(el.get(name))
print(d)

產量

{'data2': ['25', '0', '2'],
 'data3': ['23', '323', '3'],
 'value': ['12', '13', '14']}

如果您使用lxml.etree那么您可以： etree.iterparse(file, tag='Sample')在iterparse()選擇Sample元素，即， if el.tag == 'Sample'在這種情況下if el.tag == 'Sample'條件， if el.tag == 'Sample'可以刪除。