This is a known problem in the literature. It's called a stabbing query into line segments. The entries in datafile1 can be considered as line segments, while the entries in datafile2 are the points you query with. So, if you are looking for an efficient algorithm, you'd need to build a segment tree (or an interval tree) from the data in datafile1, and perform queries with the data in datafile2.

IIRC, you can build a segment tree in O (n log2 n) time, while queries take O (log2 n + k) time. So, if you have N entries in datafile1 and M entries in datafile2, your total running time would be O ((N + M) log2 N + K), where K is the number of matches. It might be that it's actually a factor of O (log N) less. This surely beats the O (N * M) approach of trying to match everything with everything.

Unfortunally, I don't think there's a module available that implements segment trees.

Abigail

In reply to Re: Code efficiency / algorithm by Abigail-II
in thread Code efficiency / algorithm by dave8775

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