Question

Given an arbitrary string, for example ("I'm going to play croquet next Friday" or "Gadzooks, is it 17th June already?"), how would you go about extracting the dates from there?

If this is looking like a good candidate for the too-hard basket, perhaps you could suggest an alternative. I want to be able to parse Twitter messages for dates. The tweets I’d be looking at would be ones which users are directing at this service, so they could be coached into using an easier format, however I’d like it to be as transparent as possible. Is there a good middle ground you could think of?

Answer 1

If you have the horsepower, you could try the following algorithm. I’m showing an example, and leaving the tedious work up to you 🙂

//Attempt to perform strtotime() on each contiguous subset of words...

//1st iteration
strtotime("Gadzooks, is it 17th June already")
strtotime("is it 17th June already")
strtotime("it 17th June already")
strtotime("17th June already")
strtotime("June already")
strtotime("already")

//2nd iteration
strtotime("Gadzooks, is it 17th June")
strtotime("is it 17th June")
strtotime("17th June") //date!
strtotime("June") //date!

//3rd iteration
strtotime("Gadzooks, is it 17th")
strtotime("is it 17th")
strtotime("it 17th")
strtotime("17th") //date!

//4th iteration
strtotime("Gadzooks, is it")
//etc

And we can assume that strtotime("17th June") is more accurate than strtotime("17th") simply because it contains more words… i.e. “next Friday” will always be more accurate than “Friday”.