fix RandomSampler & BatchSampler. test=develop (#26559)

* fix RandomSampler & BatchSampler. test=develop

python/paddle/fluid/dataloader/batch_sampler.py

@@ -16,7 +16,7 @@ from __future__ import print_function
 from __future__ import division
 
 import numpy as np
-from .sampler import Sampler, SequenceSampler
+from .sampler import Sampler, SequenceSampler, RandomSampler
 from .dataset import Dataset, IterableDataset
 
 __all__ = ["BatchSampler"]
@@ -86,7 +86,6 @@ class BatchSampler(Sampler):
             # init with sampler
             sampler = RandomSampler(RandomDataset(100))
             bs = BatchSampler(sampler=sampler,
-                              shuffle=True,
                               batch_size=8,
                               drop_last=True)
 
@@ -118,14 +117,16 @@ class BatchSampler(Sampler):
                 "dataset should not be a paddle.io.IterableDataset"
             assert sampler is None, \
                 "should not set both dataset and sampler"
-            self.sampler = SequenceSampler(dataset)
+            assert isinstance(shuffle, bool), \
+                "shuffle should be a boolean value, but got {}".format(type(shuffle))
+            if shuffle:
+                self.sampler = RandomSampler(dataset)
+            else:
+                self.sampler = SequenceSampler(dataset)
 
         assert isinstance(batch_size, int) and batch_size > 0, \
             "batch_size should be a positive integer, but got {}".format(batch_size)
         self.batch_size = batch_size
-        assert isinstance(shuffle, bool), \
-            "shuffle should be a boolean value, but got {}".format(type(shuffle))
-        self.shuffle = shuffle
         assert isinstance(drop_last, bool), \
             "drop_last should be a boolean value, but got {}".format(type(drop_last))
         self.drop_last = drop_last

python/paddle/fluid/dataloader/sampler.py

@@ -177,7 +177,7 @@ class RandomSampler(Sampler):
                 def __len__(self):
                     return self.num_samples
 
-            sampler = RandomSampler(data_souce=RandomDataset(100))
+            sampler = RandomSampler(data_source=RandomDataset(100))
 
             for index in sampler:
                 print(index)
@@ -216,7 +216,11 @@ class RandomSampler(Sampler):
     def __iter__(self):
         n = len(self.data_source)
         if self.generator:
-            for index in self.generator:
+            for i in range(self.num_samples):
+                try:
+                    index = next(self.generator)
+                except StopIteration:
+                    return
                 yield index
         else:
             if self.replacement:

python/paddle/fluid/tests/unittests/test_batch_sampler.py

@@ -88,6 +88,18 @@ class TestRandomSampler(unittest.TestCase):
             rets.append(i)
         assert tuple(sorted(rets)) == tuple(range(0, 60))
 
+    def test_with_generator_num_samples(self):
+        dataset = RandomDataset(100, 10)
+        generator = iter(range(0, 60))
+        sampler = RandomSampler(
+            dataset, generator=generator, num_samples=50, replacement=True)
+        assert len(sampler) == 50
+
+        rets = []
+        for i in iter(sampler):
+            rets.append(i)
+        assert tuple(sorted(rets)) == tuple(range(0, 50))
+
 
 class TestBatchSampler(unittest.TestCase):
     def setUp(self):