feat: add update_config functionality (#531)

* feat: add `update_config` finctionality

- sorts the config for better readability
- updates "_name_or_path" key in config with upload_repo
- sets indentation of 4 spaces
- allows adding other key-value pairs via kwargs
- reduces code duplication
- standardizes config-update across mlx-lm

* feat: standardize updating config

Impactes:
- fuse.py
- merge.py

* update formatting

* remove commented out code

* update func: update_config to save_config

- drop kwards
- rename func as save_config
- incorporate review suggestions

* update func: save_config

- ensure only config-saving functionality
- function oes not return config as a dict anymore
- added review suggestions

* fixed formatting

* update formatting instruction in contribution guide

* nits

---------

Co-authored-by: Awni Hannun <awni@apple.com>

CONTRIBUTING.md

@@ -12,7 +12,7 @@ possible.
    This should install hooks for running `black` and `clang-format` to ensure
    consistent style for C++ and python code.
  
-   You can also run the formatters manually as follows:
+   You can also run the formatters manually as follows on individual files:
  
      ```bash
      clang-format -i file.cpp
@@ -22,6 +22,16 @@ possible.
      black file.py
      ```
 
+     or,
+
+     ```bash
+     # single file
+     pre-commit run --files file1.py 
+
+     # specific files
+     pre-commit run --files file1.py file2.py
+     ```
+ 
    or run `pre-commit run --all-files` to check all files in the repo.
 
 ## Issues

llms/mlx_lm/fuse.py

@@ -9,7 +9,13 @@ from mlx.utils import tree_flatten, tree_unflatten
 
 from .tuner.lora import LoRALinear
 from .tuner.utils import apply_lora_layers, dequantize
-from .utils import fetch_from_hub, get_model_path, save_weights, upload_to_hub
+from .utils import (
+    fetch_from_hub,
+    get_model_path,
+    save_config,
+    save_weights,
+    upload_to_hub,
+)
 
 
 def parse_arguments() -> argparse.Namespace:
@@ -87,8 +93,7 @@ def main() -> None:
     if args.de_quantize:
         config.pop("quantization", None)
 
-    with open(save_path / "config.json", "w") as fid:
-        json.dump(config, fid, indent=4)
+    save_config(config, config_path=save_path / "config.json")
 
     if args.upload_repo is not None:
         hf_path = args.hf_path or (

llms/mlx_lm/merge.py

@@ -13,7 +13,13 @@ import numpy as np
 import yaml
 from mlx.utils import tree_flatten, tree_map
 
-from .utils import fetch_from_hub, get_model_path, save_weights, upload_to_hub
+from .utils import (
+    fetch_from_hub,
+    get_model_path,
+    save_config,
+    save_weights,
+    upload_to_hub,
+)
 
 
 def configure_parser() -> argparse.ArgumentParser:
@@ -151,8 +157,7 @@ def merge(
 
     tokenizer.save_pretrained(mlx_path)
 
-    with open(mlx_path / "config.json", "w") as fid:
-        json.dump(base_config, fid, indent=4)
+    save_config(config, config_path=mlx_path / "config.json")
 
     if upload_repo is not None:
         upload_to_hub(mlx_path, upload_repo, base_hf_path)

llms/mlx_lm/utils.py

@@ -553,6 +553,29 @@ def quantize_model(
     return quantized_weights, quantized_config
 
 
+def save_config(
+    config: dict,
+    config_path: Union[str, Path],
+) -> None:
+    """Save the model configuration to the ``config_path``.
+
+    The final configuration will be sorted before saving for better readability.
+
+    Args:
+        config (dict): The model configuration.
+        config_path (Union[str, Path]): Model configuration file path.
+    """
+    # Clean unused keys
+    config.pop("_name_or_path", None)
+
+    # sort the config for better readability
+    config = dict(sorted(config.items()))
+
+    # write the updated config to the config_path (if provided)
+    with open(config_path, "w") as fid:
+        json.dump(config, fid, indent=4)
+
+
 def convert(
     hf_path: str,
     mlx_path: str = "mlx_model",
@@ -588,8 +611,7 @@ def convert(
 
     tokenizer.save_pretrained(mlx_path)
 
-    with open(mlx_path / "config.json", "w") as fid:
-        json.dump(config, fid, indent=4)
+    save_config(config, config_path=mlx_path / "config.json")
 
     if upload_repo is not None:
         upload_to_hub(mlx_path, upload_repo, hf_path)