Python正则表达式：在句子中重复匹配模式

Question

I have an expression of the form

some_text_0 pattern_instance_1 some_text_1 pattern_instance_2 some_text_2 pattern_instance_3 some_text_3 ..

where each pattern_instance is an instance of PATTERN ,

and I would like to extract it as [pattern_instance_1, some_text_1], [pattern_instance_2, some_text_2], ... (dropping the first some_text_0 ).

What is the best way to do this ?

As a more concrete case I am trying to match something like

Things I need to buy: 1 banana two apples three pears zero kiwis

into

[1, banana] , [two, apples] , ..

I already have the regex to match the numbers but it's fairly complex. The few solutions I found seem to involve negating this regex to do the match on some text but I was wondering whether there would be another way, as I am not sure how to negate my regex. I also tried playing with re.find_all() but couldn't get it to work.

Answer 1

This is how I'd approach it...

1. re.finditer will give you a list of MatchObjects

2. Each MatchObject has start function that gives you the first index of the pattern. end() function is analogical.

3. Then, the only thing left is to build the tuple.

   • Create first element by retrieving the text between start() and end() indices.
   • Create the second element by retrieving the text between end() of this MatchObject and start() of the next MatchObject (or until the end of the string if that was the last MatchObject).