Python regex: greedy pattern returning multiple empty matches

Question

This pattern is meant simply to grab everything in a string up until the first potential sentence boundary in the data:

[^\\.?!\\r\\n]*

Out

Answer 1

The * quantifier allows the pattern to capture a substring of length zero. In your original code version (without the ^ anchor in front), the additional matches are:

• the zero-length string between the end of hard and the first !
• the zero-length string between the first and second !
• the zero-length string between the second and third !
• the zero-length string between the third ! and the end of the text

You can slice/dice this further if you like here.

Adding that ^ anchor to the front now ensures that only a single substring can match the pattern, since the beginning of the input text occurs exactly once.