Question

I’m currently playing with the Stack Overflow data dumps and am trying to construct (what I imagine is) a simple regular expression to extract tag names from inside of < and > characters. So, for each question, I have a list of one or more tags like <tagone><tag-two>...<tag-n> and am trying to extract just a list of tag names. Here are a few example tag strings taken from the data dump:

<javascript><internet-explorer>

<c#><windows><best-practices><winforms><windows-services>

<c><algorithm><sorting><word>

<java>

For reference, I don’t need to divide tag names into words, so for examples like <best-practices> I would like to get back best-practices (not best and practices). Also, for what it’s worth, I’m using Python if it makes any difference. Any suggestions?

Answer 1

Since the tag names of Stackoverflow do not have embedded < > you can use the regex:

<(.*?)>

or

<([^>]*)>

Explanation:

• < : A literal <
• (..) : To group and remember the
  match.
• .*? : To match anything in
  non-greedy way.
• > : A literal <
• [^>] : A char class to match
  anything other than a >