# Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserved # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. """ Optimizers(update equation) for SGD method. TODO(yuyang18): Complete comments. """ import paddle.trainer_config_helpers.config_parser_utils as config_parser_utils import paddle.trainer_config_helpers.optimizers as v1_optimizers from paddle.proto.OptimizerConfig_pb2 import OptimizerConfig __all__ = [ 'Momentum', 'Adam', 'Adamax', 'AdaGrad', 'DecayedAdaGrad', 'AdaDelta', 'RMSProp', 'ModelAverage', 'L2Regularization' ] class Optimizer(object): def __init__(self, **kwargs): import py_paddle.swig_paddle as swig_api if 'batch_size' in kwargs: del kwargs['batch_size'] # not important for python library. def __impl__(): v1_optimizers.settings(batch_size=1, **kwargs) self.__opt_conf_proto__ = config_parser_utils.parse_optimizer_config( __impl__) self.__opt_conf__ = swig_api.OptimizationConfig.createFromProto( self.__opt_conf_proto__) def enable_types(self): """ get enable_types for each optimizer. enable_types = [value, gradient, momentum, etc] For each optimizer(SGD, Adam), GradientMachine should enable different buffers. """ import py_paddle.swig_paddle as swig_api tmp = swig_api.ParameterOptimizer.create(self.__opt_conf__) assert isinstance(tmp, swig_api.ParameterOptimizer) return tmp.getParameterTypes() def __create_local_updater__(self): import py_paddle.swig_paddle as swig_api return swig_api.ParameterUpdater.createLocalUpdater(self.__opt_conf__) def __create_remote_updater__(self, pass_num, use_sparse_updater): import py_paddle.swig_paddle as swig_api return swig_api.ParameterUpdater.createRemoteUpdater( self.__opt_conf__, pass_num, use_sparse_updater) def __create_new_remote_updater__(self, pserver_spec, use_etcd): import py_paddle.swig_paddle as swig_api return swig_api.ParameterUpdater.createNewRemoteUpdater( self.__opt_conf__, pserver_spec, use_etcd) def create_updater(self, is_local, num_passes, use_sparse_updater, pserver_spec, use_etcd): """ create proper parameter_updater by configuration. :param is_local: create local or remote parameter updater :param num_passes: remote parameter updater will use this to config parameter server. :param use_sparse_updater: when use remote updater, if some parameter is sparse, updater should do some extra thing: .. code-block:: python if use_sparse_remote_updater: gradient_machine.prefetch(in_args) parameter_updater.getParametersRemote() :param pserver_spec: pserver location, eg: localhost:3000, if use etcd, pserver_spec should be the etcd endpoints, eg: http://localhost:2379 :return: parameter_updater """ if is_local: parameter_updater = self.__create_local_updater__() else: if pserver_spec is None: parameter_updater = self.__create_remote_updater__( num_passes, use_sparse_updater) else: parameter_updater = self.__create_new_remote_updater__( pserver_spec, use_etcd) return parameter_updater class Momentum(Optimizer): """ SGD Optimizer. SGD is an optimization method, trying to find a neural network that minimize the "cost/error" of it by iteration. In paddle's implementation SGD Optimizer is synchronized, which means all gradients will be wait to calculate and reduced into one gradient, then do optimize operation. The neural network consider the learning problem of minimizing an objective function, that has the form of a sum .. math:: Q(w) = \\sum_{i}^{n} Q_i(w) The value of function Q sometimes is the cost of neural network (Mean Square Error between prediction and label for example). The function Q is parametrised by w, the weight/bias of neural network. And weights is what to be learned. The i is the i-th observation in (trainning) data. So, the SGD method will optimize the weight by .. math:: w = w - \\eta \\nabla Q(w) = w - \\eta \\sum_{i}^{n} \\nabla Q_i(w) where :math:`\\eta` is learning rate. And :math:`n` is batch size. """ def __init__(self, momentum=None, sparse=False, **kwargs): learning_method = v1_optimizers.MomentumOptimizer( momentum=momentum, sparse=sparse) super(Momentum, self).__init__( learning_method=learning_method, **kwargs) class Adam(Optimizer): """ Adam optimizer. The details of please refer `Adam: A Method for Stochastic Optimization `_ .. math:: m(w, t) & = \\beta_1 m(w, t-1) + (1 - \\beta_1) \\nabla Q_i(w) \\\\ v(w, t) & = \\beta_2 v(w, t-1) + (1 - \\beta_2)(\\nabla Q_i(w)) ^2 \\\\ w & = w - \\frac{\\eta}{\\sqrt{v(w,t) + \\epsilon}} :param beta1: the :math:`\\beta_1` in equation. :type beta1: float :param beta2: the :math:`\\beta_2` in equation. :type beta2: float :param epsilon: the :math:`\\epsilon` in equation. It is used to prevent divided by zero. :type epsilon: float """ def __init__(self, beta1=0.9, beta2=0.999, epsilon=1e-8, **kwargs): learning_method = v1_optimizers.AdamOptimizer( beta1=beta1, beta2=beta2, epsilon=epsilon) super(Adam, self).__init__(learning_method=learning_method, **kwargs) class Adamax(Optimizer): """ Adamax optimizer. The details of please refer this `Adam: A Method for Stochastic Optimization `_ .. math:: m_t & = \\beta_1 * m_{t-1} + (1-\\beta_1)* \\nabla Q_i(w) \\\\ u_t & = max(\\beta_2*u_{t-1}, abs(\\nabla Q_i(w))) \\\\ w_t & = w_{t-1} - (\\eta/(1-\\beta_1^t))*m_t/u_t :param beta1: the :math:`\\beta_1` in the equation. :type beta1: float :param beta2: the :math:`\\beta_2` in the equation. :type beta2: float """ def __init__(self, beta1=0.9, beta2=0.999, **kwargs): learning_method = v1_optimizers.AdamaxOptimizer( beta1=beta1, beta2=beta2) super(Adamax, self).__init__(learning_method=learning_method, **kwargs) class AdaGrad(Optimizer): """ Adagrad(for ADAptive GRAdient algorithm) optimizer. For details please refer this `Adaptive Subgradient Methods for Online Learning and Stochastic Optimization `_. .. math:: G &= \\sum_{\\tau=1}^{t} g_{\\tau} g_{\\tau}^T \\\\ w & = w - \\eta diag(G)^{-\\frac{1}{2}} \\circ g """ def __init__(self, **kwargs): learning_method = v1_optimizers.AdaGradOptimizer() super(AdaGrad, self).__init__(learning_method=learning_method, **kwargs) class DecayedAdaGrad(Optimizer): """ AdaGrad method with decayed sum gradients. The equations of this method show as follow. .. math:: E(g_t^2) &= \\rho * E(g_{t-1}^2) + (1-\\rho) * g^2 \\\\ learning\\_rate &= 1/sqrt( ( E(g_t^2) + \\epsilon ) :param rho: The :math:`\\rho` parameter in that equation :type rho: float :param epsilon: The :math:`\\epsilon` parameter in that equation. :type epsilon: float """ def __init__(self, rho=0.95, epsilon=1e-06, **kwargs): learning_method = v1_optimizers.DecayedAdaGradOptimizer( rho=rho, epsilon=epsilon) super(DecayedAdaGrad, self).__init__( learning_method=learning_method, **kwargs) class AdaDelta(Optimizer): """ AdaDelta method. The details of adadelta please refer to this `ADADELTA: AN ADAPTIVE LEARNING RATE METHOD `_. .. math:: E(g_t^2) &= \\rho * E(g_{t-1}^2) + (1-\\rho) * g^2 \\\\ learning\\_rate &= sqrt( ( E(dx_{t-1}^2) + \\epsilon ) / ( \\ E(g_t^2) + \\epsilon ) ) \\\\ E(dx_t^2) &= \\rho * E(dx_{t-1}^2) + (1-\\rho) * (-g*learning\\_rate)^2 :param rho: :math:`\\rho` in equation :type rho: float :param epsilon: :math:`\\rho` in equation :type epsilon: float """ def __init__(self, rho=0.95, epsilon=1e-06, **kwargs): learning_method = v1_optimizers.AdaDeltaOptimizer( rho=rho, epsilon=epsilon) super(AdaDelta, self).__init__( learning_method=learning_method, **kwargs) class RMSProp(Optimizer): """ RMSProp(for Root Mean Square Propagation) optimizer. For details please refer this `slide `_. The equations of this method as follows: .. math:: v(w, t) & = \\rho v(w, t-1) + (1 - \\rho)(\\nabla Q_{i}(w))^2 \\\\ w & = w - \\frac{\\eta} {\\sqrt{v(w,t) + \\epsilon}} \\nabla Q_{i}(w) :param rho: the :math:`\\rho` in the equation. The forgetting factor. :type rho: float :param epsilon: the :math:`\\epsilon` in the equation. :type epsilon: float """ def __init__(self, rho=0.95, epsilon=1e-6, **kwargs): learning_method = v1_optimizers.RMSPropOptimizer( rho=rho, epsilon=epsilon) super(RMSProp, self).__init__(learning_method=learning_method, **kwargs) ModelAverage = v1_optimizers.ModelAverage L2Regularization = v1_optimizers.L2Regularization if __name__ == '__main__': import py_paddle.swig_paddle as swig_api swig_api.initPaddle('--use_gpu=false') for opt in [ Momentum(), Adam(), Adamax(), AdaGrad(), DecayedAdaGrad(), AdaDelta(), RMSProp(), Adam( model_average=ModelAverage(average_window=0.5), regularization=L2Regularization(rate=0.5), gradient_clipping_threshold=25) ]: print opt, opt.enable_types()