A while back I needed a way to check the weather forecast, simply, from a terminal, as is the preference of most Unix geeks like me. Being a Canadian, I'm not interested in the Weather Channel as much as the Environment Canada data. Thankfully, they do publish an RSS feed, and good for them.

I'm interested in this one: http://www.weatheroffice.gc.ca/rss/city/on-118_e.xml. So, to check the weather, I need to pull the feed and parse it. Pulling a page in Python is as simple as using urllib. From there, I can walk the elements I want like so:

import urllib
from xml.etree.ElementTree import parse

for elem in parse(urllib.urlopen(rssfeed)).findall('channel/item/title'):

Now, I wanted the option of picking a certain number of lines, and wrapping at a certain number of columns. I wanted this for using the script output as input into other apps, like Conky. Skipping lines is easy, intelligently wrapping them is not. Luckily, Python has a textwrap module in the standard library.

You use it like this:

import textwrap

wrapper = textwrap.TextWrapper(width=options.wrap, subsequent_indent="    ")
lines = wrapper.wrap(s)
for line in lines:
    print line

Put together, it's really that simple. I think the majority of my code is option parsing. The core loop is just this:

options = parse_options()
wrapper = textwrap.TextWrapper(width=options.wrap, subsequent_indent="    ")
count = 0
for elem in parse(urllib.urlopen(rssfeed)).findall('channel/item/title'):
    s = elem.text.encode('utf8', 'ignore')
    lines = wrapper.wrap(s)
    for line in lines:
        count += 1
        if options.lines and count > options.lines:
            break
        else:
            print line
    else:
        continue
    break

The whole thing is here. Sample output looks like this:

No watches or warnings in effect, Ottawa (Kanata - Orléans)
Current Conditions: Light Snow, -11.1°C
Sunday night: A few flurries. Low minus 18.
Monday: Sunny. High minus 9.
Monday night: Increasing cloudiness. Low minus 12.
Tuesday: Chance of flurries. High minus 7. POP 60%
Wednesday: A mix of sun and cloud. Low minus 16. High minus 8.
Thursday: Periods of snow. Low minus 8. High minus 2.
Friday: Sunny. Low minus 12. High minus 7.
Saturday: Periods of snow. Low minus 12. High minus 7.

I love building my own tools like this, it's the ultimate in end-user computing. Unix and Python are my playground.