[WIP][examples/seq2seq] move old s2s scripts to legacy (#10136)

* move old s2s scripts to legacy

* add the tests back

* proper rename

* restore

* Apply suggestions from code review

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

Co-authored-by: Stas Bekman <stas@stason.org>
Co-authored-by: Stas Bekman <stas00@users.noreply.github.com>
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

examples/legacy/seq2seq/convert_model_to_fp16.py

@@ -0,0 +1,36 @@
+#!/usr/bin/env python
+# Copyright 2020 The HuggingFace Team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from typing import Union
+
+import fire
+import torch
+from tqdm import tqdm
+
+
+def convert(src_path: str, map_location: str = "cpu", save_path: Union[str, None] = None) -> None:
+    """Convert a pytorch_model.bin or model.pt file to torch.float16 for faster downloads, less disk space."""
+    state_dict = torch.load(src_path, map_location=map_location)
+    for k, v in tqdm(state_dict.items()):
+        if not isinstance(v, torch.Tensor):
+            raise TypeError("FP16 conversion only works on paths that are saved state dicts, like pytorch_model.bin")
+        state_dict[k] = v.half()
+    if save_path is None:  # overwrite src_path
+        save_path = src_path
+    torch.save(state_dict, save_path)
+
+
+if __name__ == "__main__":
+    fire.Fire(convert)