Using Python to Access Web Data_Coursera_Extracting Data from XML

[fairypp]

Extracting Data from XML
In this assignment you will write a Python program somewhat similar to
http://www.pythonlearn.com/code/geoxml.py (http://www.pythonlearn.com/code/geoxml.py). The program will
prompt for a URL, read the XML data from that URL using urllib and then parse and extract the comment counts
from the XML data, compute the sum of the numbers in the file.
We provide two files for this assignment. One is a sample file where we give you the sum for your testing and the
other is the actual data you need to process for the assignment.
Sample data: http://python-data.dr-chuck.net/comments_42.xml (http://python-data.drchuck.
net/comments_42.xml) (Sum=2553)
Actual data: http://python-data.dr-chuck.net/comments_247546.xml (http://python-data.drchuck.
net/comments_247546.xml) (Sum ends with 89)
You do not need to save these files to your folder since your program will read the data directly from the URL.
Note: Each student will have a distinct data url for the assignment - so only use your own data url for analysis.
Data Format and Approach
The data consists of a number of names and comment counts in XML as follows:

Matthias
97

You are to look through all the tags and find the values sum the numbers. The closest
sample code that shows how to parse XML is geoxml.py (http://www.pythonlearn.com/code/geoxml.py). But
since the nesting of the elements in our data is different than the data we are parsing in that sample code you will
have to make real changes to the code.
To make the code a little simpler, you can use an XPath selector string to look through the entire tree of XML for
any tag named 'count' with the following line of code:
counts = tree.findall('.//count')
Take a look at the Python ElementTree documentation and look for the supported XPath syntax for details. You
could also work from the top of the XML down to the comments node and then loop through the child nodes of
the comments node.
Sample Execution
✏ Exit
×
7/19/2016 PR4E
https://pr4e.dr-chuck.com/tsugi/mod/python-data/index.php?PHPSESSID=fc7aeca2ba1db5521935917346250d45 2/2
$ python solution.py
Enter location: http://python-data.dr-chuck.net/comments_42.xml
Retrieving http://python-data.dr-chuck.net/comments_42.xml
Retrieved 4204 characters
Count: 50
Sum: 2...
Turning in the Assignment
Enter the sum from the actual data and your Python code below:
Sum: (ends with 89)

import urllib
import xml.etree.ElementTree as ET

url = 'http://python-data.dr-chuck.net/comments_247546.xml'


uh = urllib.urlopen(url)
data = uh.read()
print 'Retrieved',len(data),'characters'

tree = ET.fromstring(data)


results = tree.findall('.//count')
nums = [int(node.text) for node in results]
counts = sum(nums)
print counts

[HarshavardhanCHITTABATHINA]

Answer
Sum
End with 13
In python code