feat: add lookup index to csv loader to make retrieving the original … (#1612)

feat: add lookup index to csv loader to make retrieving the original csv
information easier using theDocument properties

langchain/document_loaders/csv.py

@@ -34,13 +34,13 @@ class CSVLoader(BaseLoader):
 
         with open(self.file_path, newline="") as csvfile:
             csv = DictReader(csvfile, **self.csv_args)  # type: ignore
-            for row in csv:
+            for i, row in enumerate(csv):
                 docs.append(
                     Document(
                         page_content="\n".join(
                             f"{k.strip()}: {v.strip()}" for k, v in row.items()
                         ),
-                        metadata={"source": self.file_path},
+                        metadata={"source": self.file_path, "row": i},
                     )
                 )