Callback

class paddle.callbacks.Callback

Callback 是一个基类，用于实现用户自定义的callback。

代码示例：

import paddle
# build a simple model checkpoint callback
class ModelCheckpoint(paddle.callbacks.Callback):
    def __init__(self, save_freq=1, save_dir=None):
        self.save_freq = save_freq
        self.save_dir = save_dir
    def on_epoch_end(self, epoch, logs=None):
        if self.model is not None and epoch % self.save_freq == 0:
            path = '{}/{}'.format(self.save_dir, epoch)
            print('save checkpoint at {}'.format(path))
            self.model.save(path)