Python Xml Parsing for Wolfram Api

Question

I'm trying to get the out put of the wolfram api using a python xml parsing script. Here's my script:

import urllib
import urllib.request
import xml.etree.ElementTree as ET

xml_data=urllib.request.urlopen("http://api.wolframalpha.com/v2/query?input=sqrt+2&appid=APLTT9-9WG78GYE65").read()
root = ET.fromstring(xml_data)

for child in root:
   print (child.get("title"))
   print (child.attrib)

I know It's only getting the attributes of everything in the title portion of the code but it's a start.

Here's a snippet of the output:

<pod title="Input" scanner="Identity" id="Input" position="100" error="false" numsubpods="1">
 <subpod title="">
 <plaintext>sqrt(2)</plaintext>

I'm trying to get it to only print out what is in the tags. Does anyone know how to edit the code to get that?

So you want `sqrt(2)` printed? – Martijn Pieters Mar 15 '13 at 21:13 — Martijn Pieters, Mar 15 '13 at 21:13

score 2 · Accepted Answer · answered Mar 15 '13 at 21:16

Only the <plaintext> elements contain text:

for pt in root.findall('.//plaintext'):
    if pt.text:
        print(pt.text)

The .text attribute holds the text of an element.

For your URL, that prints:

sqrt(2)
1.4142135623730950488016887242096980785696718753769480...
[1; 2^_]
Pythagoras's constant
sqrt(2)~~1.4142  (real, principal root)
-sqrt(2)~~-1.4142  (real root)

It looks like the <pod> tags have interesting titles too:

for pod in root.findall('.//pod'):
    print(pod.attrib['title'])
    for pt in pod.findall('.//plaintext'):
        if pt.text:
            print('-', pt.text)

which then prints:

Input
- sqrt(2)
Decimal approximation
- 1.4142135623730950488016887242096980785696718753769480...
Number line
Continued fraction
- [1; 2^_]
Constant name
- Pythagoras's constant
All 2nd roots of 2
- sqrt(2)~~1.4142  (real, principal root)
- -sqrt(2)~~-1.4142  (real root)
Plot of all roots in the complex plane

That's exactly what I wanted. Thank you! – user1985351 Mar 15 '13 at 21:19 — user1985351, Mar 15 '13 at 21:19

score 0 · Answer 2 · answered Sep 02 '14 at 11:01

Some more examples :

 import httplib2
 import xml.etree.ElementTree as ET


def request(query):
    query = urllib.urlencode({'input':query})
    app_id = "Q6254U-URKKHH9JLL"
    wolfram_api = "http://api.wolframalpha.com/v2/query?appid="+app_id+"&format=plaintext&podtitle=Result&"+query
    resp, content = httplib2.Http().request(wolfram_api)
    return content

def response(query):
    content = request(query)    
    root = ET.fromstring(content)
    error = root.get('error')
    success = root.get('success')
    numpods = root.get('numpods')
    answer= ''
    if success and int(numpods) > 0 :
        for plaintext in root.iter('plaintext'):
            if isinstance(plaintext.text, str) :
                answer = answer + plaintext.text
        return answer
    elif error:
        return "sorry I don't know that"
request("How old is the queen")

Python Xml Parsing for Wolfram Api

2 Answers2