Merge pull request #479 from littletomatodonkey/add_piecewise

add piecewise decay

doc/doc_ch/config.md

@@ -60,6 +60,8 @@
 |         beta1           |    设置一阶矩估计的指数衰减率  |       0.9         |               \             |
 |         beta2           |    设置二阶矩估计的指数衰减率  |     0.999         |               \             |
 |         decay           |         是否使用decay       |    \              |               \             |
-|      function(decay)    |         设置decay方式       |   cosine_decay    |       目前只支持cosin_decay  |
-|      step_each_epoch    |      每个epoch包含多少次迭代  |         20       | 计算方式：total_image_num / (batch_size_per_card * card_size) |
-|        total_epoch      |    总共迭代多少个epoch        |       1000      | 与Global.epoch_num 一致        |
+|      function(decay)    |         设置decay方式       |   -    |       目前支持cosine_decay与piecewise_decay  |
+|      step_each_epoch    |      每个epoch包含多少次迭代, cosine_decay时有效   |         20       | 计算方式：total_image_num / (batch_size_per_card * card_size) |
+|        total_epoch      |    总共迭代多少个epoch, cosine_decay时有效        |       1000      | 与Global.epoch_num 一致        |
+|        boundaries      |    学习率下降时的迭代次数间隔, piecewise_decay时有效       |       -      | 参数为列表形式        |
+|        decay_rate      |    学习率衰减系数, piecewise_decay时有效       |       -      |  \        |

doc/doc_en/config_en.md

@@ -60,6 +60,8 @@ Take `rec_icdar15_train.yml` as an example:
 |         beta1           |    Set the exponential decay rate for the 1st moment estimates  |       0.9         |               \             |
 |         beta2           |    Set the exponential decay rate for the 2nd moment estimates  |     0.999         |               \             |
 |         decay           |         Whether to use decay       |    \              |               \             |
-|      function(decay)    |         Set the decay function       |   cosine_decay    |           Only support cosine_decay            |
-|      step_each_epoch    |      The number of steps in an epoch.  |         20       | Calculation ：total_image_num / (batch_size_per_card * card_size) |
-|        total_epoch      |    The number of epochs      |       1000      | Consistent with Global.epoch_num      |
+|      function(decay)    |         Set the decay function       |   cosine_decay    |         Support cosine_decay and piecewise_decay            |
+|      step_each_epoch    |      The number of steps in an epoch. Used in cosine_decay  |         20       | Calculation ：total_image_num / (batch_size_per_card * card_size) |
+|        total_epoch      |    The number of epochs. Used in cosine_decay      |       1000      | Consistent with Global.epoch_num      |
+|        boundaries      |    The step intervals to reduce learning rate. Used in piecewise_decay       |       -      |  The format is list        |
+|        decay_rate      |    Learning rate decay rate. Used in piecewise_decay       |       -      |  \        |

ppocr/data/rec/img_tools.py

@@ -360,7 +360,7 @@ def process_image(img,
         text = char_ops.encode(label)
         if len(text) == 0 or len(text) > max_text_length:
             logger.info(
-                "Warning in ppocr/data/rec/img_tools.py:line362: Wrong data type."
+                "Warning in ppocr/data/rec/img_tools.py: Wrong data type."
                 "Excepted string with length between 1 and {}, but "
                 "got '{}'. Label is '{}'".format(max_text_length,
                                                  len(text), label))

ppocr/optimizer.py

@@ -36,17 +36,28 @@ def AdamDecay(params, parameter_list=None):
     l2_decay = params.get("l2_decay", 0.0)
 
     if 'decay' in params:
+        supported_decay_mode = ["cosine_decay", "piecewise_decay"]
         params = params['decay']
         decay_mode = params['function']
+        assert decay_mode in supported_decay_mode, "Supported decay mode is {}, but got {}".format(
+            supported_decay_mode, decay_mode)
+
+        if decay_mode == "cosine_decay":
             step_each_epoch = params['step_each_epoch']
             total_epoch = params['total_epoch']
-        if decay_mode == "cosine_decay":
             base_lr = fluid.layers.cosine_decay(
                 learning_rate=base_lr,
                 step_each_epoch=step_each_epoch,
                 epochs=total_epoch)
-        else:
-            logger.info("Only support Cosine decay currently")
+        elif decay_mode == "piecewise_decay":
+            boundaries = params["boundaries"]
+            decay_rate = params["decay_rate"]
+            values = [
+                base_lr * decay_rate**idx
+                for idx in range(len(boundaries) + 1)
+            ]
+            base_lr = fluid.layers.piecewise_decay(boundaries, values)
+
     optimizer = fluid.optimizer.Adam(
         learning_rate=base_lr,
         beta1=beta1,