Checking whether scala set intersection is empty

Question

Is there a recommended way to check whether two scala collection Sets have a non-empty intersection? There is of course the obvious

set1.intersect(set2).isEmpty

But that actually constructs the intersection set first, unless I am mistaken. Is there a better/faster way?

Answer 1

The idiomatic way is to use .intersect() or .diff() but both ways build new collection internally.

Fastest ways are:

• Manually iterate over first set until match in the second
• Use probabilistic Bloom Filter that take some time to construct it but can compare two sets (even very huge) very fast (occasionally may give false positives)