!1608 add get_dataset_size for CelebADataset

Merge pull request !1608 from yanghaitao/yht_celeba_get_dataset_size_r0.3

mindspore/dataset/engine/datasets.py

@@ -4036,6 +4036,30 @@ class CelebADataset(MappableDataset):
 
         return self.sampler.is_sharded()
 
+    def get_dataset_size(self):
+        """
+        Get the number of batches in an epoch.
+
+        Return:
+            Number, number of batches.
+        """
+        if self._dataset_size is None:
+            dir = os.path.realpath(self.dataset_dir)
+            attr_file = os.path.join(dir, "list_attr_celeba.txt")
+            num_rows = ''
+            try:
+                with open(attr_file, 'r') as f:
+                    num_rows = int(f.readline())
+            except Exception:
+                raise RuntimeError("Get dataset size failed from attribution file.")
+            rows_per_shard = get_num_rows(num_rows, self.num_shards)
+            if self.num_samples is not None:
+                rows_per_shard = min(self.num_samples, rows_per_shard)
+            rows_from_sampler = self._get_sampler_dataset_size()
+            if rows_from_sampler is None:
+                return rows_per_shard
+            return min(rows_from_sampler, rows_per_shard)
+        return self._dataset_size
 
 class TextFileDataset(SourceDataset):
     """

tests/ut/python/dataset/test_datasets_celeba.py

@@ -85,9 +85,14 @@ def test_celeba_dataset_distribute():
         count = count + 1
     assert (count == 1)
 
+def test_celeba_get_dataset_size():
+    data = ds.CelebADataset(DATA_DIR, decode=True, shuffle=False)
+    size = data.get_dataset_size()
+    assert size == 2
 
 if __name__ == '__main__':
     test_celeba_dataset_label()
     test_celeba_dataset_op()
     test_celeba_dataset_ext()
     test_celeba_dataset_distribute()
+    test_celeba_get_dataset_size()