Basic Python file searching and I/O

Question

Hello,

I'm trying to complete a simple task in Python and I'm new to the language (I'm C++). I hope someone might be able to point me in the right direction.

Problem: I have an XML file (12mb) full of data and within the file there are start tags 'xmltag' and end tags '/xmltag' that represent the start and end of the data sections I would like to pull out.

I would like to navigate through this open file with a loop and for each instance locate a start tag and copy the data within the section to a new file until the end tag. I would then like to repeat this to the end of the file.

I'm happy with the file I/O but not the most efficient looping, searching and extracting of the data.

I really like the look of the language and hopefully I'm going to get more involved so I can give back to the community.

Big thanks!

Answer 1

Check BeautifulSoup

from BeautifulSoup import BeautifulSoup

with open('bigfile.xml', 'r') as xml:
    soup = BeautifulSoup(xml):
    for xmltag in soup('xmltag'):
        print xmltag.contents

Answer 2

Dive Into Python 3 have a great chapter about this:

• http://diveintopython3.org/xml.html#xml-parse

It'a great free book about python, worth reading !

Answer 3

xml=open("xmlfile").read()
x=xml.split("</xmltag>")
for block in x:
    if "<xmltag>" in block:
        print block.split("<xmltag>")[-1]

Answer 4

No need to install BeautifulSoup, Python includes the ElementTree parser in its standard library.

from xml.etree import cElementTree as ET
tree = ET.parse('myfilename')
new_tree = ET('new_root_element')
for element in tree.findall('.//xmltag'):
    new_tree.append(tree.element)
print ET.tostring(new_tree)

Answer 5

The BeautifulSoup answer is good but this executes faster and doesn't require an external library:

import xml.etree.cElementTree as ET
tree = ET.parse('xmlfile.xml')
results = (elem for elem in tree.getiterator('xmltag'))

# in Python 2.7+, getiterator() is deprecated; use tree.iter('xmltag')