add sample

Author: lyuwenyu

paddlemix/datacopilot/core/dataset.py

@@ -122,6 +122,11 @@ def shuffle(self, seed: Optional[int]=None) -> 'MMDataset':
             random.shuffle(self._items)
         return self
 
+    def sample(self, k: int) -> 'MMDataset':
+        indices = random.sample(range(len(self)), k)
+        items = [self.items[i] for i in indices]
+        return MMDataset(items)
+
     @classmethod
     def from_json(cls, path: str, schema: SCHEMA=SCHEMA.MM) -> 'MMDataset':
         with open(path, 'r') as f: