model definition update

models/yolo.py

@@ -45,13 +45,15 @@ class Detect(nn.Module):
 
 
 class Model(nn.Module):
-    def __init__(self, model_yaml='yolov5s.yaml'):  # cfg, number of classes, depth-width gains
+    def __init__(self, model_yaml='yolov5s.yaml', ch=3, nc=None):  # model, input channels, number of classes
         super(Model, self).__init__()
         with open(model_yaml) as f:
             self.md = yaml.load(f, Loader=yaml.FullLoader)  # model dict
+            if nc:
+                self.md['nc'] = nc  # override yaml value
 
         # Define model
-        self.model, self.save, ch = parse_model(self.md, ch=[3])  # model, savelist, ch_out
+        self.model, self.save, ch = parse_model(self.md, ch=[ch])  # model, savelist, ch_out
         # print([x.shape for x in self.forward(torch.zeros(1, 3, 64, 64))])
 
         # Build strides, anchors