Fix potential issue with change to num_classes arg in train/validate.py defaulting to None (rely on model def / default_cfg)

timm/models/helpers.py

@@ -198,6 +198,7 @@ def load_pretrained(model, cfg=None, num_classes=1000, in_chans=3, filter_fn=Non
 
     classifier_name = cfg['classifier']
     if num_classes == 1000 and cfg['num_classes'] == 1001:
+        # FIXME this special case is problematic as number of pretrained weight sources increases
         # special case for imagenet trained models with extra background class in pretrained weights
         classifier_weight = state_dict[classifier_name + '.weight']
         state_dict[classifier_name + '.weight'] = classifier_weight[1:]

train.py

@@ -337,6 +337,9 @@ def main():
         bn_eps=args.bn_eps,
         scriptable=args.torchscript,
         checkpoint_path=args.initial_checkpoint)
+    if args.num_classes is None:
+        assert hasattr(model, 'num_classes'), 'Model must have `num_classes` attr if not set on cmd line/config.'
+        args.num_classes = model.num_classes  # FIXME handle model default vs config num_classes more elegantly
 
     if args.local_rank == 0:
         _logger.info('Model %s created, param count: %d' %

validate.py

@@ -137,6 +137,9 @@ def validate(args):
         in_chans=3,
         global_pool=args.gp,
         scriptable=args.torchscript)
+    if args.num_classes is None:
+        assert hasattr(model, 'num_classes'), 'Model must have `num_classes` attr if not set on cmd line/config.'
+        args.num_classes = model.num_classes
 
     if args.checkpoint:
         load_checkpoint(model, args.checkpoint, args.use_ema)