Update train(hyp, *args) to accept hyp file or dict (#3668)

train.py

@@ -39,12 +39,11 @@
 logger = logging.getLogger(__name__)
 
 
-def train(hyp,
+def train(hyp,  # path/to/hyp.yaml or hyp dictionary
           opt,
           device,
           tb_writer=None
           ):
-    logger.info(colorstr('hyperparameters: ') + ', '.join(f'{k}={v}' for k, v in hyp.items()))
     save_dir, epochs, batch_size, total_batch_size, weights, rank, single_cls = \
         Path(opt.save_dir), opt.epochs, opt.batch_size, opt.total_batch_size, opt.weights, opt.global_rank, \
         opt.single_cls
@@ -56,6 +55,12 @@ def train(hyp,
     best = wdir / 'best.pt'
     results_file = save_dir / 'results.txt'
 
+    # Hyperparameters
+    if isinstance(hyp, str):
+        with open(hyp) as f:
+            hyp = yaml.safe_load(f)  # load hyps dict
+    logger.info(colorstr('hyperparameters: ') + ', '.join(f'{k}={v}' for k, v in hyp.items()))
+
     # Save run settings
     with open(save_dir / 'hyp.yaml', 'w') as f:
         yaml.safe_dump(hyp, f, sort_keys=False)
@@ -529,10 +534,6 @@ def train(hyp,
         assert not opt.image_weights, '--image-weights argument is not compatible with DDP training'
         opt.batch_size = opt.total_batch_size // opt.world_size
 
-    # Hyperparameters
-    with open(opt.hyp) as f:
-        hyp = yaml.safe_load(f)  # load hyps
-
     # Train
     logger.info(opt)
     if not opt.evolve:
@@ -541,7 +542,7 @@ def train(hyp,
             prefix = colorstr('tensorboard: ')
             logger.info(f"{prefix}Start with 'tensorboard --logdir {opt.project}', view at http://localhost:6006/")
             tb_writer = SummaryWriter(opt.save_dir)  # Tensorboard
-        train(hyp, opt, device, tb_writer)
+        train(opt.hyp, opt, device, tb_writer)
 
     # Evolve hyperparameters (optional)
     else:
@@ -575,6 +576,8 @@ def train(hyp,
                 'mosaic': (1, 0.0, 1.0),  # image mixup (probability)
                 'mixup': (1, 0.0, 1.0)}  # image mixup (probability)
 
+        with open(opt.hyp) as f:
+            hyp = yaml.safe_load(f)  # load hyps dict
         assert opt.local_rank == -1, 'DDP mode not implemented for --evolve'
         opt.notest, opt.nosave = True, True  # only test/save final epoch
         # ei = [isinstance(x, (int, float)) for x in hyp.values()]  # evolvable indices