Keep n largest values compared by f

[stevengj]

@foobar_lv2

You don’t need a min-max heap, you just need the minimal value (if the new value is larger than the current min, and you have 1000 values, then pop the old min and push the value).

As I commented in the other thread, you can (in principle) do better than this by combining the pop and push operations: Maintaining a fixed size "top N" values list - #7 by stevengj (and that implementation also accepts an arbitrary Ordering).