model.yaml nc inherited from dataset.yaml

models/yolo.py

@@ -52,7 +52,8 @@ class Model(nn.Module):
                 self.md = yaml.load(f, Loader=yaml.FullLoader)  # model dict
 
         # Define model
-        if nc:
+        if nc and nc != self.md['nc']:
+            print('Overriding %s nc=%g with nc=%g' % (model_cfg, self.md['nc'], nc))
             self.md['nc'] = nc  # override yaml value
         self.model, self.save = parse_model(self.md, ch=[ch])  # model, savelist, ch_out
         # print([x.shape for x in self.forward(torch.zeros(1, ch, 64, 64))])

train.py

@@ -77,8 +77,7 @@ def train(hyp):
         os.remove(f)
 
     # Create model
-    model = Model(opt.cfg).to(device)
-    assert model.md['nc'] == nc, '%s nc=%g classes but %s nc=%g classes' % (opt.data, nc, opt.cfg, model.md['nc'])
+    model = Model(opt.cfg, nc=data_dict['nc']).to(device)
 
     # Image sizes
     gs = int(max(model.stride))  # grid size (max stride)