Add some clearer error messages

lib/data/dataset.py

@@ -46,7 +46,7 @@ class DataSet(tordata.Dataset):
             data_list.append(_)
         for data in data_list:
             if len(data) != len(data_list[0]):
-                raise AssertionError
+                raise ValueError('Each input data should have the same length.')
 
         return data_list
 

lib/data/sampler.py

@@ -63,7 +63,7 @@ class InferenceSampler(tordata.sampler.Sampler):
         rank = dist.get_rank()
 
         if batch_size % world_size != 0:
-            raise AssertionError("World size({}) need be divisible by batch_size({})".format(
+            raise ValueError("World size({}) is not divisible by batch_size({})".format(
                 world_size, batch_size))
 
         if batch_size != 1: