Download/parse historical NZ opinion poll results

def get_mediawiki_source(article_title):
    import urllib, json
    params = { "format":"json", "action":"query", "prop":"revisions", "rvprop":"timestamp|user|comment|content" }
    params["titles"] = "%s" % urllib.quote(article_title.encode("utf8"))
    qs = "&".join("%s=%s" % (k, v)  for k, v in params.items())
    url = "http://en.wikipedia.org/w/api.php?%s" % qs
    fp = urllib.urlopen(url)
    jsondata = json.load(fp)
    return jsondata['query']['pages'].values()[0]['revisions'][-1]['*']

def prettyprint(cell, depth=0):
    print '  ' * depth, cell
    for child in cell.children:
        prettyprint(child, depth+2)

def cellvalue(cell):
    from mwlib import parser
    articlelink = cell.find(parser.ArticleLink)
    if articlelink:
        cell = articlelink[0]
    while not isinstance(cell, parser.Text):
        if cell.children:
            cell = cell.children[0]
        else:
            break
    value = cell.asText().strip()
    try:
        value = float(value)
    except:
        pass
    return value

import sys, csv, codecs, cStringIO
class UnicodeWriter:
    """
    A CSV writer which will write rows to CSV file "f",
    which is encoded in the given encoding.
    """

    def __init__(self, f, dialect=csv.excel, encoding="utf-8", **kwds):
        # Redirect output to a queue
        self.queue = cStringIO.StringIO()
        self.writer = csv.writer(self.queue, dialect=dialect, **kwds)
        self.stream = f
        self.encoder = codecs.getincrementalencoder(encoding)()

    def writerow(self, row):
        self.writer.writerow([s.encode("utf-8") for s in row])
        # Fetch UTF-8 output from the queue ...
        data = self.queue.getvalue()
        data = data.decode("utf-8")
        # ... and reencode it into the target encoding
        data = self.encoder.encode(data)
        # write to the target stream
        self.stream.write(data)
        # empty queue
        self.queue.truncate(0)

    def writerows(self, rows):
        for row in rows:
            self.writerow(row)

if __name__=="__main__":
    import sys
    from mwlib.refine import compat as mw
    from mwlib import parser
    title = "Opinion polling for the New Zealand general election, 2005"
    pollresult_section_title = 'Individual polls'
    article = get_mediawiki_source(title)
    #get the rows from the first table found
    rows = mw.parse_txt(article).find(parser.Table)[0].find(parser.Row)
    nicerows = [[cellvalue(cell) for cell in r.find(parser.Cell)] for r in rows]
    finalrows = [row for row in nicerows if len(row) > 2] #remove non-data rows

    writer = UnicodeWriter(sys.stdout)
    for row in finalrows:
        row = [unicode(item) for item in row]
        writer.writerow(row)