[Doc] Refine code an docstrings

ppsci/utils/misc.py

@@ -210,6 +210,11 @@ class Timer(ContextDecorator):
         ...     w = sum(range(0, 10))
         >>> func()  # doctest: +SKIP
 
+        >>> timer = misc.Timer("cost_of_func", auto_print=False)
+        >>> timer.start()
+        >>> func()
+        >>> timer.end()
+        >>> print(f"time cost of 'cost_of_func' is {timer.interval:.2f}")
     """
 
     interval: float  # Time cost for code within Timer context
@@ -220,10 +225,31 @@ def __init__(self, name: str = "Timer", auto_print: bool = True):
         self.auto_print = auto_print
 
     def __enter__(self):
+        paddle.device.synchronize()
         self.start_time = time.perf_counter()
         return self
 
     def __exit__(self, type, value, traceback):
+        paddle.device.synchronize()
+        self.end_time = time.perf_counter()
+        self.interval = self.end_time - self.start_time
+        if self.auto_print:
+            logger.message(f"{self.name}.time_cost = {self.interval:.2f} s")
+
+    def start(self, name: str = "Timer"):
+        """Push a new timer context.
+
+        Args:
+            name (str, optional): Name of code block to be clocked. Defaults to "Timer".
+        """
+        paddle.device.synchronize()
+        self.start_time = time.perf_counter()
+
+    def end(self):
+        """
+        End current timer context and print time cost.
+        """
+        paddle.device.synchronize()
         self.end_time = time.perf_counter()
         self.interval = self.end_time - self.start_time
         if self.auto_print:

ppsci/utils/save_load.py

@@ -146,7 +146,18 @@ def load_checkpoint(
             equation_dict = paddle.load(f"{path}.pdeqn")
 
     # set state dict
-    model.set_state_dict(param_dict)
+    missing_keys, unexpected_keys = model.set_state_dict(param_dict)
+    if missing_keys:
+        logger.warning(
+            f"There are missing keys when loading checkpoint: {missing_keys}, "
+            "and corresponding parameters will be initialized by default."
+        )
+    if unexpected_keys:
+        logger.warning(
+            f"There are redundant keys: {unexpected_keys}, "
+            "and corresponding weights will be ignored."
+        )
+
     optimizer.set_state_dict(optim_dict)
     if grad_scaler is not None:
         grad_scaler.load_state_dict(scaler_dict)

ppsci/utils/symbolic.py

@@ -101,7 +101,7 @@
     sp.sign: paddle.sign,
     sp.ceiling: paddle.ceil,
     sp.floor: paddle.floor,
-    # NOTE: sp.Add and sp.Mul is not included here for un-alignment with sympy
+    # NOTE: sp.Add and sp.Mul is not included here for un-alignment with paddle
     # and are implemented manually in 'OperatorNode._add_operator_func' and
     # 'OperatorNode._mul_operator_func'
 }
@@ -711,15 +711,15 @@ def lambdify(
             such as 'momentum_x'. Defaults to None.
         create_graph (bool, optional): Whether to create the gradient graphs of
             the computing process. When it is True, higher order derivatives are
-            supported to compute; when it is False, the gradient graphs of the
+            supported to compute. When it is False, the gradient graphs of the
             computing process would be discarded. Defaults to True.
         retain_graph (Optional[bool]): Whether to retain the forward graph which
             is used to calculate the gradient. When it is True, the graph would
             be retained, in which way users can calculate backward twice for the
             same graph. When it is False, the graph would be freed. Defaults to None,
             which means it is equal to `create_graph`.
         fuse_derivative (bool, optional): Whether to fuse the derivative nodes.
-            for example, if `expr` is 'Derivative(u, x) + Derivative(u, y)'
+            For example, if `expr` is 'Derivative(u, x) + Derivative(u, y)'
             It will compute grad(u, x) + grad(u, y) if fuse_derivative=False,
             else will compute sum(grad(u, [x, y])) if fuse_derivative=True as is more
             efficient in backward-graph. Defaults to False, as it is experimental so not