fix lr scheduler

ppgan/solver/lr_scheduler.py

@@ -12,25 +12,8 @@ def build_lr_scheduler(cfg):
                 0, epoch + 1 - cfg.start_epoch) / float(cfg.decay_epochs + 1)
             return lr_l
 
-        scheduler = paddle.optimizer.lr_scheduler.LambdaLR(
-            cfg.learning_rate, lr_lambda=lambda_rule)
+        scheduler = paddle.optimizer.lr.LambdaLR(cfg.learning_rate,
+                                                 lr_lambda=lambda_rule)
         return scheduler
     else:
         raise NotImplementedError
-
-
-# paddle.optimizer.lr_scheduler
-class LinearDecay(paddle.optimizer.lr_scheduler._LRScheduler):
-    def __init__(self, learning_rate, step_per_epoch, start_epoch,
-                 decay_epochs):
-        super(LinearDecay, self).__init__()
-        self.learning_rate = learning_rate
-        self.start_epoch = start_epoch
-        self.decay_epochs = decay_epochs
-        self.step_per_epoch = step_per_epoch
-
-    def step(self):
-        cur_epoch = int(self.step_num // self.step_per_epoch)
-        decay_rate = 1.0 - max(
-            0, cur_epoch + 1 - self.start_epoch) / float(self.decay_epochs + 1)
-        return self.create_lr_var(decay_rate * self.learning_rate)