Question

What would be the best way to do this.

The input string is

<133_3><135_3><116_2>The other system worked for about 1 month</116_2> got some good images <137_3>on it then it started doing the same thing as the first one</137_3> so then I quit using either camera now they are just sitting and collecting dust.</135_3></133_3> 

the expected output is

{'The other system worked for about 1 month got some good images on it then it started doing the same thing as the first one so then I quit \ using either camera now they are just sitting and collecting dust.':[133, 135],  'The other system worked for about 1 month': [116],  'on it then it started doing the same thing as the first one':[137]  } 

that seems like a recursive regexp search but I can’t figure out how exactly.

I can think of a tedious recursive function as of now, but have a feeling that there should be a better way.

Related question: Can regular expressions be used to match nested patterns?

Answer 1

Use expat or another XML parser; it’s more explicit than anything else, considering you’re dealing with XML data anyway.

However, note that XML element names can’t start with a number as your example has them.

Here’s a parser that will do what you need, although you’ll need to tweak it to combine duplicate elements into one dict key:

from xml.parsers.expat import ParserCreate  open_elements = {} result_dict = {}  def start_element(name, attrs):     open_elements[name] = True  def end_element(name):     del open_elements[name]  def char_data(data):     for element in open_elements:         cur = result_dict.setdefault(element, '')         result_dict[element] = cur + data  if __name__ == '__main__':     p = ParserCreate()      p.StartElementHandler = start_element     p.EndElementHandler = end_element     p.CharacterDataHandler = char_data      p.Parse(u'<_133_3><_135_3><_116_2>The other system worked for about 1 month</_116_2> got some good images <_137_3>on it then it started doing the same thing as the first one</_137_3> so then I quit using either camera now they are just sitting and collecting dust.</_135_3></_133_3>', 1)      print result_dict