如何使用Python 3.2

Question

我有這樣的XML格式.....

<event timestamp="0.447463" bustype="LIN" channel="LIN 1"> 
<col name="Time"/> 
<col name="Start of Frame">0.440708</col> 
<col name="Channel">LIN 1</col> 
<col name="Dir">Tx</col> 
<col name="Event Type">LIN Frame (Diagnostic Request)</col> 
<col name="Frame Name">MasterReq_DB</col> 
<col name="Id">3C</col> 
<col name="Data">81 06 04 04 FF FF 50 4C</col> 
<col name="Publisher">TestMaster (simulated)</col> 
<col name="Checksum">D3 &quot;Classic&quot;</col> 
<col name="Header Duration">2.090 ms (40.1 bits)</col> 
<col name="Resp. Duration">4.688 ms (90.0 bits)</col> 
<col name="Time difference">0.049987</col> 
<empty/> 
</event> 

在上面的XML中提取與XML文件的屬性相關聯的數據，我需要提取具有屬性「名稱」
相關數據我能夠得到所有的名字，但我無法提取> MasterReq_DB <場
請幫我...提前
感謝

我的Python代碼...

import sys 
import array 
import string 
from xml.dom.minidom import parse,parseString 
from xml.dom import minidom            
input_file = open("test_input.txt",'r')             
alines = input_file.read() 
word_lst = alines.split("'") 
filename = word_lst[1] 
pathname=word_lst[3]            
f = open(pathname,'r') 
doc = minidom.parse(f) 
node = doc.documentElement 
events = doc.getElementsByTagName('event') 
for event in events: 
    #print (event) 
    columns = event.getElementsByTagName('col') 
    for column in columns: 
     #print (column) 
     head = column.getAttribute('name') 
     if (head == ('Frame Name')): 
      print (head) 
      request = head.firstChild.wholeText 
      print (request) 
print ("DOne") 

Answer 1

這裏有一個底，讓你開始與lxml，如果你想：

In [1]: x = '''<event timestamp="0.447463" bustype="LIN" channel="LIN 1"> 
    ...: <col name="Time"/> 
    ...: <col name="Start of Frame">0.440708</col> 
    ...: <col name="Channel">LIN 1</col> 
    ...: <col name="Dir">Tx</col> 
    ...: <col name="Event Type">LIN Frame (Diagnostic Request)</col> 
    ...: <col name="Frame Name">MasterReq_DB</col> 
    ...: <col name="Id">3C</col> 
    ...: <col name="Data">81 06 04 04 FF FF 50 4C</col> 
    ...: <col name="Publisher">TestMaster (simulated)</col> 
    ...: <col name="Checksum">D3 &quot;Classic&quot;</col> 
    ...: <col name="Header Duration">2.090 ms (40.1 bits)</col> 
    ...: <col name="Resp. Duration">4.688 ms (90.0 bits)</col> 
    ...: <col name="Time difference">0.049987</col> 
    ...: <empty/> 
    ...: </event> ''' 

In [2]: from lxml import etree 

In [3]: tree = etree.fromstring(x) 

In [4]: [elem.text for elem in tree.xpath('//*[@name]')] 
Out[4]: 
[None, 
'0.440708', 
'LIN 1', 
'Tx', 
'LIN Frame (Diagnostic Request)', 
'MasterReq_DB', 
'3C', 
'81 06 04 04 FF FF 50 4C', 
'TestMaster (simulated)', 
'D3 "Classic"', 
'2.090 ms (40.1 bits)', 
'4.688 ms (90.0 bits)', 
'0.049987'] 

In [5]: [name for name in tree.xpath('//@name')] 
Out[5]: 
['Time', 
'Start of Frame', 
'Channel', 
'Dir', 
'Event Type', 
'Frame Name', 
'Id', 
'Data', 
'Publisher', 
'Checksum', 
'Header Duration', 
'Resp. Duration', 
'Time difference'] 

從文件而不是字符串讀取，使用lxml.etree.parse功能。

這是鏈接到lxml tutorial。這是XPath syntax的參考。