updated the code to avoid deepcopy()

intermediate_source/mario_rl_tutorial.py

@@ -424,7 +424,23 @@ def __init__(self, input_dim, output_dim):
         if w != 84:
             raise ValueError(f"Expecting input width: 84, got: {w}")
 
-        self.online = nn.Sequential(
+        self.online = self._build_cnn(input_dim, output_dim)
+        self.target = self._build_cnn(input_dim, output_dim)
+
+        # Q_target parameters are frozen.
+        for p in self.target.parameters():
+            p.requires_grad = False
+
+    def forward(self, input, model):
+        if model == "online":
+            return self.online(input)
+        elif model == "target":
+            return self.target(input)
+
+    def _build_cnn(self, input_dim, output_dim):
+        c, _, _ = input_dim
+
+        cnn = nn.Sequential(
             nn.Conv2d(in_channels=c, out_channels=32, kernel_size=8, stride=4),
             nn.ReLU(),
             nn.Conv2d(in_channels=32, out_channels=64, kernel_size=4, stride=2),
@@ -437,17 +453,7 @@ def __init__(self, input_dim, output_dim):
             nn.Linear(512, output_dim),
         )
 
-        self.target = copy.deepcopy(self.online)
-
-        # Q_target parameters are frozen.
-        for p in self.target.parameters():
-            p.requires_grad = False
-
-    def forward(self, input, model):
-        if model == "online":
-            return self.online(input)
-        elif model == "target":
-            return self.target(input)
+        return cnn
 
 
 ######################################################################