Avoid flattening hyperparameters in WandbLogger (#17574)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

(cherry picked from commit 6c8c02d)

src/lightning/pytorch/CHANGELOG.md

@@ -20,6 +20,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Fixed signature inspection of decorated hooks ([#17507](https://github.com/Lightning-AI/lightning/pull/17507))
 
 
+- The `WandbLogger` no longer flattens dictionaries in the hyperparameters logged to the dashboard ([#17574](https://github.com/Lightning-AI/lightning/pull/17574))
+
+
 
 ## [2.0.2] - 2023-04-24
 

src/lightning/pytorch/loggers/wandb.py

@@ -24,7 +24,7 @@
 from lightning_utilities.core.imports import RequirementCache
 from torch import Tensor
 
-from lightning.fabric.utilities.logger import _add_prefix, _convert_params, _flatten_dict, _sanitize_callable_params
+from lightning.fabric.utilities.logger import _add_prefix, _convert_params, _sanitize_callable_params
 from lightning.fabric.utilities.types import _PATH
 from lightning.pytorch.callbacks.model_checkpoint import ModelCheckpoint
 from lightning.pytorch.loggers.logger import Logger, rank_zero_experiment
@@ -418,7 +418,6 @@ def watch(self, model: nn.Module, log: str = "gradients", log_freq: int = 100, l
     @rank_zero_only
     def log_hyperparams(self, params: Union[Dict[str, Any], Namespace]) -> None:
         params = _convert_params(params)
-        params = _flatten_dict(params)
         params = _sanitize_callable_params(params)
         self.experiment.config.update(params, allow_val_change=True)
 

tests/tests_pytorch/loggers/test_wandb.py

@@ -103,10 +103,9 @@ def test_wandb_logger_init(wandb, monkeypatch):
     wandb.init().log.assert_called_with({"acc": 1.0, "trainer/global_step": 6})
 
     # log hyper parameters
-    logger.log_hyperparams({"test": None, "nested": {"a": 1}, "b": [2, 3, 4]})
-    wandb.init().config.update.assert_called_once_with(
-        {"test": None, "nested/a": 1, "b": [2, 3, 4]}, allow_val_change=True
-    )
+    hparams = {"test": None, "nested": {"a": 1}, "b": [2, 3, 4]}
+    logger.log_hyperparams(hparams)
+    wandb.init().config.update.assert_called_once_with(hparams, allow_val_change=True)
 
     # watch a model
     logger.watch("model", "log", 10, False)