mindspore.dataset.WaitedDSCallback

class mindspore.dataset.WaitedDSCallback(step_size=1)

阻塞式数据处理回调类的抽象基类，用于与训练回调类 mindspore.Callback 的同步。

可用于在step或epoch开始前执行自定义的回调方法，例如在自动数据增强中根据上一个epoch的loss值来更新增强算子参数配置。

用户可通过 train_run_context 获取网络训练相关信息，如 network 、 train_network 、 epoch_num 、 batch_num 、 loss_fn 、 optimizer 、 parallel_mode 、 device_number 、 list_callback 、 cur_epoch_num 、 cur_step_num 、 dataset_sink_mode 、 net_outputs 等，详见 mindspore.Callback 。

用户可通过 ds_run_context 获取数据处理管道相关信息，包括 cur_epoch_num (当前epoch数)、 cur_step_num_in_epoch (当前epoch的step数)、 cur_step_num (当前step数)。

Note

注意，第2个step或epoch开始时才会触发该调用。

参数：

• step_size (int, optional) - 每个step包含的数据行数。通常step_size与batch_size一致，默认值：1。

样例：

>>> import mindspore.nn as nn
>>> import mindspore as ms
>>> from mindspore.dataset import WaitedDSCallback
>>> import mindspore.dataset as ds
>>>
>>> ms.set_context(mode=ms.GRAPH_MODE, device_target="CPU")
>>>
>>> # custom callback class for data synchronization in data pipeline
>>> class MyWaitedCallback(WaitedDSCallback):
...     def __init__(self, events, step_size=1):
...         super().__init__(step_size)
...         self.events = events
...
...     # callback method to be executed by data pipeline before the epoch starts
...     def sync_epoch_begin(self, train_run_context, ds_run_context):
...         event = f"ds_epoch_begin_{ds_run_context.cur_epoch_num}_{ds_run_context.cur_step_num}"
...         self.events.append(event)
...
...     # callback method to be executed by data pipeline before the step starts
...     def sync_step_begin(self, train_run_context, ds_run_context):
...         event = f"ds_step_begin_{ds_run_context.cur_epoch_num}_{ds_run_context.cur_step_num}"
...         self.events.append(event)
>>>
>>> # custom callback class for data synchronization in network training
>>> class MyMSCallback(ms.Callback):
...     def __init__(self, events):
...         self.events = events
...
...     # callback method to be executed by network training after the epoch ends
...     def epoch_end(self, run_context):
...         cb_params = run_context.original_args()
...         event = f"ms_epoch_end_{cb_params.cur_epoch_num}_{cb_params.cur_step_num}"
...         self.events.append(event)
...
...     # callback method to be executed by network training after the step ends
...     def step_end(self, run_context):
...         cb_params = run_context.original_args()
...         event = f"ms_step_end_{cb_params.cur_epoch_num}_{cb_params.cur_step_num}"
...         self.events.append(event)
>>>
>>> # custom network
>>> class Net(nn.Cell):
...     def construct(self, x, y):
...         return x
>>>
>>> # define a parameter that needs to be synchronized between data pipeline and network training
>>> events = []
>>>
>>> # define callback classes of data pipeline and netwok training
>>> my_cb1 = MyWaitedCallback(events, 1)
>>> my_cb2 = MyMSCallback(events)
>>> arr = [1, 2, 3, 4]
>>>
>>> # construct data pipeline
>>> data = ds.NumpySlicesDataset((arr, arr), column_names=["c1", "c2"], shuffle=False)
>>> # map the data callback object into the pipeline
>>> data = data.map(operations=(lambda x: x), callbacks=my_cb1)
>>>
>>> net = Net()
>>> model = ms.Model(net)
>>>
>>> # add the data and network callback objects to the model training callback list
>>> model.train(2, data, dataset_sink_mode=False, callbacks=[my_cb2, my_cb1])

sync_epoch_begin(train_run_context, ds_run_context)

用于定义在数据epoch开始前，训练epoch结束后执行的回调方法。

参数：

• train_run_context：包含前一个epoch的反馈信息的网络训练运行信息。

• ds_run_context：数据处理管道运行信息。

sync_step_begin(train_run_context, ds_run_context)

用于定义在数据step开始前，训练step结束后执行的回调方法。

参数：

• train_run_context：包含前一个step的反馈信息的网络训练运行信息。

• ds_run_context：数据处理管道运行信息。