Space efficient strategy for k_smallest_by_key

Author: ejmount

src/lib.rs

@@ -2766,13 +2766,7 @@ pub trait Itertools : Iterator {
         F: Fn(&Self::Item) -> K,
         K: Ord,
     {
-        let iter = self.map(|v| (key(&v), v));
-
-        let results: Vec<_> =
-            crate::k_smallest::k_smallest_general(iter, k, |(k, _), (l, _)| k.cmp(&l))
-                .map(|(_, t)| t)
-                .collect();
-        results.into_iter()
+        self.k_smallest_by(k, |a,b| key(&a).cmp(&key(&b)))
     }
 
     /// Sort the k largest elements into a new iterator, in descending order.