update: valid the condition

samplers.py

@@ -22,6 +22,8 @@ class RASampler(torch.utils.data.Sampler):
             if not dist.is_available():
                 raise RuntimeError("Requires distributed package to be available")
             rank = dist.get_rank()
+        if num_repeats < 1:
+            raise ValueError("num_repeats should be greater than 0")
         self.dataset = dataset
         self.num_replicas = num_replicas
         self.rank = rank