How to use a decaying learning rate with an estimator in tensorflow?

匿名 (未验证) 提交于 2019-12-03 00:59:01

问题:

I am trying to use a LinearClassifier with a GradientDescentOptimizer with a decaying learning rate.

My code:

def main(): # load data     features = np.load('data/feature_data.npz')     tx = features['arr_0']     y = features['arr_1']  ## Prepare logistic regression     n_point, n_feat = tx.shape  # Input functions     def get_input_fn_from_numpy(tx, y, num_epochs=None, shuffle=True):     # Preprocess data         return tf.estimator.inputs.numpy_input_fn(         x={"x":tx},         y=y,         num_epochs=num_epochs,         shuffle=shuffle,         batch_size=128         )      cols_label = "x"     feature_cols = [tf.contrib.layers.real_valued_column(cols_label)]      my_input_fn_train = get_input_fn_from_numpy(tx, y)      model_dir = 'data/tmp/' + datetime.datetime.now().strftime("%m-%d_%H:%M:%S")     global_step = tf.Variable(0, trainable=False)     learning_rate=tf.train.exponential_decay(0.001*np.ones((20,1), dtype=np.float32), global_step, 10000, 0.95, staircase=False)     regressor = tf.contrib.learn.LinearClassifier(feature_columns=feature_cols,                                               model_dir=model_dir,                                                   optimizer=tf.train.GradientDescentOptimizer(learning_rate=learning_rate))      regressor.fit(input_fn=get_input_fn_from_numpy(tx_train, y_train), steps=100000)     results = regressor.evaluate(input_fn=my_input_fn_test) 

I get the error:

  File "training.py", line 71, in <module> main()   File "training.py", line 63, in main regressor.fit(input_fn=get_input_fn_from_numpy(tx_train, y_train), steps=100000)   File "/lib/python3.6/site-packages/tensorflow/python/util/deprecation.py", line 296, in new_func return func(*args, **kwargs)   File "/lib/python3.6/site-packages/tensorflow/contrib/learn/python/learn/estimators/estimator.py", line 458, in fit loss = self._train_model(input_fn=input_fn, hooks=hooks)   File "/lib/python3.6/site-packages/tensorflow/contrib/learn/python/learn/estimators/estimator.py", line 958, in _train_model model_fn_ops = self._get_train_ops(features, labels)  File "/lib/python3.6/site-packages/tensorflow/contrib/learn/python/learn/estimators/estimator.py", line 1165, in _get_train_ops return self._call_model_fn(features, labels, model_fn_lib.ModeKeys.TRAIN)   File "/lib/python3.6/site-packages/tensorflow/contrib/learn/python/learn/estimators/estimator.py", line 1136, in _call_model_fn model_fn_results = self._model_fn(features, labels, **kwargs)   File "/lib/python3.6/site-packages/tensorflow/contrib/learn/python/learn/estimators/linear.py", line 186, in _linear_model_fn logits=logits)   File "/lib/python3.6/site-packages/tensorflow/contrib/learn/python/learn/estimators/head.py", line 854, in create_model_fn_ops enable_centered_bias=self._enable_centered_bias)   File "/lib/python3.6/site-packages/tensorflow/contrib/learn/python/learn/estimators/head.py", line 649, in _create_model_fn_ops batch_size, loss_fn, weight_tensor)   File "/lib/python3.6/site-packages/tensorflow/contrib/learn/python/learn/estimators/head.py", line 1911, in _train_op train_op = train_op_fn(loss)   File "/lib/python3.6/site-packages/tensorflow/contrib/learn/python/learn/estimators/linear.py", line 179, in _train_op_fn zip(grads, my_vars), global_step=global_step))   File "/lib/python3.6/site-packages/tensorflow/python/training/optimizer.py", line 456, in apply_gradients update_ops.append(processor.update_op(self, grad))   File "/lib/python3.6/site-packages/tensorflow/python/training/optimizer.py", line 97, in update_op return optimizer._apply_dense(g, self._v)  # pylint: disable=protected-access   File "/lib/python3.6/site-packages/tensorflow/python/training/gradient_descent.py", line 50, in _apply_dense use_locking=self._use_locking).op   File "/lib/python3.6/site-packages/tensorflow/python/training/gen_training_ops.py", line 370, in apply_gradient_descent name=name)   File "/lib/python3.6/site-packages/tensorflow/python/framework/op_def_library.py", line 330, in apply_op g = ops._get_graph_from_inputs(_Flatten(keywords.values()))   File "/lib/python3.6/site-packages/tensorflow/python/framework/ops.py", line 4262, in _get_graph_from_inputs _assert_same_graph(original_graph_element, graph_element)   File "/lib/python3.6/site-packages/tensorflow/python/framework/ops.py", line 4201, in _assert_same_graph "%s must be from the same graph as %s." % (item, original_item)) ValueError: Tensor("ExponentialDecay:0", shape=(20, 1), dtype=float32) must be from the same graph as Tensor("linear/x/weight/part_0:0", shape=(20, 1), dtype=float32_ref). 

I am using tensorflow 1.3. It works if i replace the learning rate by a constant, say 0.01. I have used a decaying learning rate in the past in combination with minimize operation but was trying to use it within LinearClassifier. I see that something seems inconsistent in the fact that I don't link the global step to the step in the fit, but was wondering how this can work. I suppose I could use a placeholder as suggested here but I don't see why I should code the update rule myself if i don't need to.

Any suggestions on how to solve this ?

回答1:

Have you tried to get the global_step by calling tf.train.get_global_step()? This should return the global_step used by your LinearClassifier model.

Instead of

global_step = tf.Variable(0, trainable=False) 

use

global_step = tf.train.get_global_step() 

This worked for me using my own Estimator class, where I use the tf.train.MomentumOptimizer to minimize the tf.nn.sparse_softmax_cross_entropy_with_logits.



易学教程内所有资源均来自网络或用户发布的内容,如有违反法律规定的内容欢迎反馈
该文章没有解决你所遇到的问题?点击提问,说说你的问题,让更多的人一起探讨吧!