Question

I am trying to add a xml file in a dict. Now What i want to do is to update the value into the dict without losing the value. Reason for this is I want to group the xml file to show all the changes made by the tag author.

Here is a sample of the xml file.

<log> 
<logentry 
revision="33185"> 
<author>glv</author> 
<date>2012-08-06T21:01:52.494219Z</date> 
<paths> 

<path 
kind="file" 
action="M">/branches/Patch_4_2_0_Branch/text.xml</path>    

<path 
kind="dir" 
action="M">/branches/Patch_4_2_0_Branch</path> 

</paths> 
<msg>PATCH_BRANCH:N/A 
BUG_NUMBER:N/A 
FEATURE_AFFECTED:N/A 
OVERVIEW:N/A 
Adding the SVN log size requirement to the branch  
</msg> 
</logentry> 
 .... 
</log> 

Here is the code I have for it written in Python.

from xml.dom import minidom 
import smtplib 
from email.mime.text import MIMEText 
from datetime import datetime 

def xml_data (): 

f = open('C:\opidea_2.xml', 'r') 

data = f.read() 

f.close() 

dom = minidom.parseString(data) 

ic = (dom.getElementsByTagName('logentry')) 

dom = None       
content = '' 
author = {}   
for num in ic: 

authors = num.getElementsByTagName('author') 

if len(authors) > 0: 

  name = authors[0].firstChild.nodeValue 

  author.update({'author': str(name)})  

datef = [] 
xmlDate = num.getElementsByTagName('date')[0].firstChild.nodeValue 
datef = [Good_Time] 
path_change = []  
paths = [x for x in num.getElementsByTagName("paths")[0].childNodes if isinstance(x, minidom.Element)] 

for path in paths:  

  x = path.childNodes[0].nodeValue   

if str(path.getAttribute("kind")) == 'dir': 

  path_change ='Directory location: ' + [str(x)] 
else:  
  path_change ='Filename: ' + [str(x)] 

xmlMsgf = [] 
xmlMsg = num.getElementsByTagName('msg') 


if xmlMsg !='' and len(xmlMsg) > 0: 
  xmlMsgc = xmlMsg[0].firstChild.nodeValue 
  xmlMsgf = [xmlMsgc] 


 else: 
   xmlMsgc = "No comment made." 
   xmlMsgf = [xmlMsgc] 

 authorentry.push{('author',authorA),('date',datef),('path',path_change),('path',xmlMsgf))}           

    for k, v in [(authorentry)]:

        try:

            author[k].append(v)

        except KeyError:

            author[k] = [v]

 author.update({'Date':datef,'Path':path_change,'msg':str(xmlMsgf)}) 
 print author

if __name__ == "__main__": 
  xml_data () 

Now what I want the end result to be is like this

Key 1 = glv , date1 ,path 1a path 1b , msg1 , date2 , path 2 , msg 2 , …

key 2 = jsm , date1 , path 1 , msg 1.

I want to group the author.update({‘Date’:datef,’Path’:path_change,’msg’:str(xmlMsgf)}) to list the xml file by the authors to append the next set of things the author made. Not very sure how to go about that. Any help would be appreciated. Here is my updated code but I seem to now get an invalid syntax error:

  line 151
    authorentry.push{('author',authorA),('date',datef),('path',path_change),('path',xmlMsgf))}           
                    ^
 SyntaxError: invalid syntax

Answer 1

You cannot ‘keep old values’ in a dict, each key has exactly one value associated with it.

You can use aggregate value types in dict’s though, for instance you can use a list as the values, and each time you find a bit of data to add, append it to the associated list.

data = {}

for k, v in [('a', 1), ('a', 2), ('b', 3)]:
    try:
        data[k].append(v)
    except KeyError:
        data[k] = [v]  # a list of one element!

There’s a convenience constructor in the collections module that can make this even easier:

import collections

data = collections.defaultdict(list)
for k, v in [('a', 1), ('a', 2), ('b', 3)]:
    data[k].append(v)