!1922 check parameter num_samples of sampler

Merge pull request !1922 from yanghaitao/yht_check_num_samples_sampler

mindspore/dataset/engine/samplers.py

@@ -218,6 +218,11 @@ class DistributedSampler(BuiltinSampler):
         if not isinstance(shuffle, bool):
             raise ValueError("shuffle should be a boolean value, but got shuffle={}".format(shuffle))
 
+        if num_samples is not None:
+            if num_samples <= 0:
+                raise ValueError("num_samples should be a positive integer "
+                                 "value, but got num_samples={}".format(num_samples))
+
         self.num_shards = num_shards
         self.shard_id = shard_id
         self.shuffle = shuffle
@@ -282,6 +287,11 @@ class PKSampler(BuiltinSampler):
         if not isinstance(shuffle, bool):
             raise ValueError("shuffle should be a boolean value, but got shuffle={}".format(shuffle))
 
+        if num_samples is not None:
+            if num_samples <= 0:
+                raise ValueError("num_samples should be a positive integer "
+                                 "value, but got num_samples={}".format(num_samples))
+
         self.num_val = num_val
         self.shuffle = shuffle
         self.class_column = class_column # work for minddataset
@@ -385,6 +395,16 @@ class SequentialSampler(BuiltinSampler):
     """
 
     def __init__(self, start_index=None, num_samples=None):
+        if num_samples is not None:
+            if num_samples <= 0:
+                raise ValueError("num_samples should be a positive integer "
+                                 "value, but got num_samples={}".format(num_samples))
+
+        if start_index is not None:
+            if start_index < 0:
+                raise ValueError("start_index should be a positive integer "
+                                 "value or 0, but got start_index={}".format(start_index))
+
         self.start_index = start_index
         super().__init__(num_samples)
 
@@ -430,6 +450,11 @@ class SubsetRandomSampler(BuiltinSampler):
     """
 
     def __init__(self, indices, num_samples=None):
+        if num_samples is not None:
+            if num_samples <= 0:
+                raise ValueError("num_samples should be a positive integer "
+                                 "value, but got num_samples={}".format(num_samples))
+
         if not isinstance(indices, list):
             indices = [indices]
 

tests/ut/python/dataset/test_sampler.py

@@ -43,7 +43,6 @@ def test_sequential_sampler(print_res=False):
 
     assert test_config(num_samples=3, num_repeats=None) == [0, 1, 2]
     assert test_config(num_samples=None, num_repeats=2) == [0, 1, 2, 3, 4] * 2
-    assert test_config(num_samples=0, num_repeats=2) == [0, 1, 2, 3, 4] * 2
     assert test_config(num_samples=4, num_repeats=2) == [0, 1, 2, 3] * 2