machine-learning.rebalancing: Don't use a distribution for equal rebalancing.

extra/machine-learning/rebalancing/rebalancing.factor

@@ -22,12 +22,14 @@ MEMO: probabilities-seq ( seq -- seq' )
 : stratified-sample ( stratified-sequences probability-sequence -- elt )
     probabilities-quot call swap nth random ; inline
 
+: equal-stratified-sample ( stratified-sequences -- elt )
+    random random ; inline
+
 : balance-labels ( X y n -- X' y' )
     [
         dup [ ] collect-index-by
-        values dup length equal-probabilities
-        '[
-            _ _ _ _ stratified-sample
+        values '[
+            _ _ _ equal-stratified-sample
             '[ _ swap nth ] bi@ 2array
         ]
     ] dip swap replicate [ keys ] [ values ] bi ;