!30961 add comments for history and lambda callbacks

Merge pull request !30961 from liutongtong9/code_docs_cbcomment

docs/api/api_python/train/mindspore.train.callback.History.rst

@@ -0,0 +1,24 @@
+.. py:class:: mindspore.train.callback.History()
+
+    将网络输出的相关信息记录到 `History` 对象中。
+
+    如果用户不自定义训练网络或评估网络，记录的内容将为损失值；如果用户自定义了训练网络/评估网络，如果定义的网络返回 `Tensor` 或 `numpy.ndarray`，则记录此返回值均值，如果返回 `tuple` 或 `list`，则记录第一个元素。
+
+    .. note::
+        通常使用在 `mindspore.Model.train` 中。
+
+    .. py:method:: begin(run_context)
+
+        训练开始时初始化History对象的epoch属性。
+
+        **参数：**
+
+        - **run_context** (RunContext) - 包含模型的一些基本信息。
+
+    .. py:method:: epoch_end(run_context)
+
+        epoch结束时记录网络输出的相关信息。
+
+        **参数：**
+
+        - **run_context** (RunContext) - 包含模型的一些基本信息。

docs/api/api_python/train/mindspore.train.callback.LambdaCallback.rst

@@ -0,0 +1,16 @@
+.. py:class:: mindspore.train.callback.LambdaCallback()
+
+    用于自定义简单的callback。
+
+    使用匿名函数构建callback，定义的匿名函数将在 `mindspore.Model.{train | eval}` 的对应阶段被调用。
+
+    请注意，callback的每个阶段都需要一个位置参数：`run_context`。
+
+    **参数：**
+
+    - **epoch_begin** (Function) - 每个epoch开始时被调用。
+    - **epoch_end** (Function) - 每个epoch结束时被调用。
+    - **step_begin** (Function) - 每个step开始时被调用。
+    - **step_end** (Function) - 每个step结束时被调用。
+    - **begin** (Function) - 模型训练、评估开始时被调用。
+    - **end** (Function) - 模型训练、评估结束时被调用。

mindspore/python/mindspore/train/callback/_history.py

@@ -20,10 +20,12 @@ from ._callback import Callback
 
 class History(Callback):
     """
-    Records the first element of network outputs into a `History` object.
+    Records the network outputs information into a `History` object.
 
-    The first element of network outputs is the loss value if not
-    custimizing the train network or eval network.
+    The network outputs information will be the loss value if not custimizing the train network or eval network;
+    if the custimized network returns a `Tensor` or `numpy.ndarray`, the mean value of network output
+    will be recorded, if the custimized network returns a `tuple` or `list`, the first element of network
+    outputs will be recorded.
 
     Note:
         Normally used in `mindspore.Model.train`.

mindspore/python/mindspore/train/callback/_lambda_callback.py

@@ -26,12 +26,12 @@ class LambdaCallback(Callback):
     Note that each stage of callbacks expects one positional arguments: `run_context`.
 
     Args:
-        epoch_begin: called at the beginning of every epoch.
-        epoch_end: called at the end of every epoch.
-        step_begin: called at the beginning of every batch.
-        step_end: called at the end of every batch.
-        begin: called at the beginning of model train/eval.
-        end: called at the end of model train/eval.
+        epoch_begin (Function): called at the beginning of every epoch.
+        epoch_end (Function): called at the end of every epoch.
+        step_begin (Function): called at the beginning of every batch.
+        step_end (Function): called at the end of every batch.
+        begin (Function): called at the beginning of model train/eval.
+        end (Function): called at the end of model train/eval.
 
     Example:
         >>> from mindspore import Model, nn

mindspore/python/mindspore/train/model.py

@@ -940,7 +940,8 @@ class Model:
         if isinstance(self._eval_network, nn.GraphCell) and dataset_sink_mode:
             raise ValueError("Sink mode is currently not supported when evaluating with a GraphCell.")
 
-        if callbacks and (isinstance(callbacks, History) or any(isinstance(cb, History) for cb in callbacks)):
+        if (isinstance(callbacks, Callback) and isinstance(callbacks, History)) or \
+                (isinstance(callbacks, list) and any(isinstance(cb, History) for cb in callbacks)):
             logger.warning("History callback is recommended to be used in training process.")
 
         cb_params = _InternalCallbackParam()