Vizsage

Mr. XKCD is correct in this. (My friend Dr. Larsson has been saying this all along). As I'm moving from data munging to data working-with, I've been moving from perl to python. Recommended:

• lxml is a beautiful interface for dealing with XML in Python. You get XPath and validation and namespaces and all that hooha but you don't have to think hard and you don't have to write SAX stream parsers or walk a DOM path. You just say crap like

  from lxml    import etree   
  from urllib2 import urlopen
  # Load file
  uri   = "http://vizsage.com/apps/baseball/results/parkinfo/parkinfo-all.xml"
  parks = etree.ElementTree(file=urlopen(uri))
  # for each park (<park> tag anywhere in document)
  for (idx, park) in enumerate(parks.xpath('//park')): 
    # dump its id, time of service and name (@attr is XPath for 'corresponding attribute')
    print ' -- '.join(
      [ s+': '+','.join(park.xpath('@'+s)) 
        for s in ('parkID', 'beg', 'end', 'games', 'name',) 
      ])
  

  and you get this in return

  parkID: MIL01 -- beg: 1878-05-14 -- end: 1878-09-14 -- games: 25   -- name: Milwaukee Base-Ball Grounds
  parkID: MIL02 -- beg: 1884-09-27 -- end: 1885-09-25 -- games: 14   -- name: Wright Street Grounds
  parkID: MIL03 -- beg: 1891-09-10 -- end: 1891-10-04 -- games: 20   -- name: Borchert Field
  parkID: MIL04 -- beg: 1901-05-03 -- end: 1901-09-12 -- games: 70   -- name: Lloyd Street Grounds
  parkID: MIL05 -- beg: 1953-04-14 -- end: 2000-09-28 -- games: 3484 -- name: County Stadium
  parkID: MIL06 -- beg: 2001-04-06 -- end: NULL       -- games: 486  -- name: Miller Park

• lxml.objectify is the replacement for perl's XML::Simple we've all been looking for. You just say gimme and it pulls in an XML file as the corresponding do-what-I-mean data structure (identical elements become arrays, tree leaves become atoms, tree structures become maps).
• Kid Templating is a great solution for XML transmogrifying, and I think I like it much better than XSLT. It looks perfect for your "Anything => XML" purposes, which is the hard part. I suppose XSLT can do the "XML => anything" tasks but those always look like stunts; the whole point of XML is that "Turn XML into whatever" tasks are easy, especially given a simple API like lxml or lxml.objectify.

Labels: databinding, element, kid, perl, python, templating, tree, xml, xslt

Posted by flip on Wednesday, December 5, 2007 at 12/05/2007 04:17:00 PM | Permalink