Code Refactor ruff check --fix --extend-select I (#13093)

* Refactor code for speed and clarity

* Auto-format by https://ultralytics.com/actions

* Update train.py

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>

* Update README.md

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>

---------

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>
Co-authored-by: UltralyticsAssistant <web@ultralytics.com>
Co-authored-by: Ultralytics Assistant <135830346+UltralyticsAssistant@users.noreply.github.com>

classify/train.py

@@ -178,7 +178,9 @@ def train(opt, device):
     # Scheduler
     lrf = 0.01  # final lr (fraction of lr0)
     # lf = lambda x: ((1 + math.cos(x * math.pi / epochs)) / 2) * (1 - lrf) + lrf  # cosine
-    lf = lambda x: (1 - x / epochs) * (1 - lrf) + lrf  # linear
+    def lf(x):
+        return (1 - x / epochs) * (1 - lrf) + lrf  # linear
+
     scheduler = lr_scheduler.LambdaLR(optimizer, lr_lambda=lf)
     # scheduler = lr_scheduler.OneCycleLR(optimizer, max_lr=lr0, total_steps=epochs, pct_start=0.1,
     #                                    final_div_factor=1 / 25 / lrf)