diff --git a/doc/fluid/user_guides/howto/dygraph/DyGraph.md b/doc/fluid/user_guides/howto/dygraph/DyGraph.md new file mode 100644 index 0000000000000000000000000000000000000000..1b75113e7d0addb63b294521a1c51575920481fc --- /dev/null +++ b/doc/fluid/user_guides/howto/dygraph/DyGraph.md @@ -0,0 +1,591 @@ +# DyGraph + +PaddlePaddle的DyGraph模式是一种动态的图执行机制,可以立即执行结果,无需构建整个图。同时,和以往静态的执行计算图不同,DyGraph模式下您的所有操作可以立即获得执行结果,而不必等待所构建的计算图全部执行完成,这样可以让您更加直观地构建PaddlePaddle下的深度学习任务,以及进行模型的调试,同时还减少了大量用于构建静态计算图的代码,使得您编写、调试网络的过程变得更加便捷。 + + + +PaddlePaddle DyGraph是一个更加灵活易用的模式,可提供: + +* 更加灵活便捷的代码组织结构: 使用python的执行控制流程和面向对象的模型设计 + + +* 更加便捷的调试功能: 直接调用操作从而检查正在运行的模型并且测试更改 + + +* 和静态执行图通用的模型代码:同样的模型代码可以使用更加便捷的DyGraph调试,执行,同时也支持使用原有的静态图模式执行 + + +* 支持纯Python和Numpy语法实现的layer: 支持使用Numpy相关操作直接搭建模型计算部分 + +## 设置和基本用法 + +1. 升级到最新的PaddlePaddle 1.4: + + pip install -q --upgrade paddlepaddle==1.4 + +2. 使用`fluid.dygraph.guard(place=None)` 上下文: + + import paddle.fluid as fluid + with fluid.dygraph.guard(): + # write your executable dygraph code here + + 现在您就可以在`fluid.dygraph.guard()`上下文环境中使用DyGraph的模式运行网络了,DyGraph将改变以往PaddlePaddle的执行方式: 现在他们将会立即执行,并且将计算结果返回给Python。 + + + Dygraph将非常适合和Numpy一起使用,使用`fluid.dygraph.base.to_variable(x)`将会将ndarray转换为`fluid.Variable`,而使用`fluid.Variable.numpy()`将可以把任意时刻获取到的计算结果转换为Numpy`ndarray`: + + x = np.ones([2, 2], np.float32) + with fluid.dygraph.guard(): + inputs = [] + for _ in range(10): + inputs.append(fluid.dygraph.base.to_variable(x)) + ret = fluid.layers.sums(inputs) + print(ret.numpy()) + + + [[10. 10.] + [10. 10.]] + + Process finished with exit code 0 + + + > 这里创建了一系列`ndarray`的输入,执行了一个`sum`操作之后,我们可以直接将运行的结果打印出来 + + 然后通过调用`reduce_sum`后使用`Variable.backward()`方法执行反向,使用`Variable.gradient()`方法即可获得反向网络执行完成后的梯度值的`ndarray`形式: + + loss = fluid.layers.reduce_sum(ret) + loss.backward() + print(loss.gradient()) + + + + [1.] + + Process finished with exit code 0 + + + + +## 基于DyGraph构建网络 + +1. 编写一段用于DyGraph执行的Object-Oriented-Designed, PaddlePaddle模型代码主要由以下**三个部分**组成: **请注意,如果您设计的这一层结构是包含参数的,则必需要使用继承自`fluid.Layer`的Object-Oriented-Designed的类来描述该层的行为。** + + + 1. 建立一个可以在DyGraph模式中执行的,Object-Oriented的网络,需要继承自`fluid.Layer`,其中需要调用基类的`__init__`方法,并且实现带有参数`name_scope`(用来标识本层的名字)的`__init__`构造函数,在构造函数中,我们通常会执行一些例如参数初始化,子网络初始化的操作,执行这些操作时不依赖于输入的动态信息: + + class MyLayer(fluid.Layer): + def __init__(self, name_scope): + super(MyLayer, self).__init__(name_scope) + + 2. 实现一个`forward(self, *inputs)`的执行函数,该函数将负责执行实际运行时网络的执行逻辑, 该函数将会在每一轮训练/预测中被调用,这里我们将执行一个简单的`relu` -> `elementwise add` -> `reduce sum`: + + def forward(self, inputs): + x = fluid.layers.relu(inputs) + self._x_for_debug = x + x = fluid.layers.elementwise_mul(x, x) + x = fluid.layers.reduce_sum(x) + return [x] + + 3. (可选)实现一个`build_once(self, *inputs)` 方法,该方法将作为一个单次执行的函数,用于初始化一些依赖于输入信息的参数和网络信息, 例如在`FC`(fully connected layer)当中, 需要依赖输入的`shape`初始化参数, 这里我们并不需要这样的操作,仅仅为了展示,因此这个方法可以直接跳过: + + def build_once(self, input): + pass + +2. 在`fluid.dygraph.guard()`中执行: + + 1. 使用Numpy构建输入: + + np_inp = np.array([1.0, 2.0, -1.0], dtype=np.float32) + + 2. 输入转换并执行前向网络获取返回值: 使用`fluid.dygraph.base.to_variable(np_inp)`转换Numpy输入为DyGraph接收的输入,然后使用`l(var_inp)[0]`调用callable object并且获取了`x`作为返回值,利用`x.numpy()`方法直接获取了执行得到的`x`的`ndarray`返回值。 + + + with fluid.dygraph.guard(): + var_inp = fluid.dygraph.base.to_variable(np_inp) + l = MyLayer("my_layer") + x = l(var_inp)[0] + dy_out = x.numpy() + + 3. 计算梯度:自动微分对于实现机器学习算法(例如用于训练神经网络的反向传播)来说很有用, 使用`x.backward()`方法可以从某个`fluid.Varaible`开始执行反向网络,同时利用`l._x_for_debug.gradient()`获取了网络中`x`梯度的`ndarray` 返回值: + + x.backward() + dy_grad = l._x_for_debug.gradient() + + + +## 使用DyGraph训练模型 + +接下来我们将以“手写数字识别”这个最基础的模型为例,展示如何利用DyGraph模式搭建并训练一个模型: + +有关手写数字识别的相关理论知识请参考[PaddleBook](https://github.com/PaddlePaddle/book/tree/develop/02.recognize_digits)中的内容,我们在这里默认您已经了解了该模型所需的深度学习理论知识。 + + +1. 准备数据,我们使用`paddle.dataset.mnist`作为训练所需要的数据集: + + train_reader = paddle.batch( + paddle.dataset.mnist.train(), batch_size=BATCH_SIZE, drop_last=True) + +2. 构建网络,虽然您可以根据之前的介绍自己定义所有的网络结构,但是您也可以直接使用`fluid.Layer.nn`当中我们为您定制好的一些基础网络结构,这里我们利用`fluid.Layer.nn.Conv2d`以及`fluid.Layer.nn.Pool2d`构建了基础的`SimpleImgConvPool`: + + class SimpleImgConvPool(fluid.dygraph.Layer): + def __init__(self, + name_scope, + num_channels, + num_filters, + filter_size, + pool_size, + pool_stride, + pool_padding=0, + pool_type='max', + global_pooling=False, + conv_stride=1, + conv_padding=0, + conv_dilation=1, + conv_groups=1, + act=None, + use_cudnn=False, + param_attr=None, + bias_attr=None): + super(SimpleImgConvPool, self).__init__(name_scope) + + self._conv2d = Conv2D( + self.full_name(), + num_channels=num_channels, + num_filters=num_filters, + filter_size=filter_size, + stride=conv_stride, + padding=conv_padding, + dilation=conv_dilation, + groups=conv_groups, + param_attr=None, + bias_attr=None, + use_cudnn=use_cudnn) + + self._pool2d = Pool2D( + self.full_name(), + pool_size=pool_size, + pool_type=pool_type, + pool_stride=pool_stride, + pool_padding=pool_padding, + global_pooling=global_pooling, + use_cudnn=use_cudnn) + + def forward(self, inputs): + x = self._conv2d(inputs) + x = self._pool2d(x) + return x + + + + > 注意: 构建网络时子网络的定义和使用请在`__init__`中进行, 而子网络的调用则在`forward`函数中调用 + + + + +3. 利用已经构建好的`SimpleImgConvPool`组成最终的`MNIST`网络: + + class MNIST(fluid.dygraph.Layer): + def __init__(self, name_scope): + super(MNIST, self).__init__(name_scope) + + self._simple_img_conv_pool_1 = SimpleImgConvPool( + self.full_name(), 1, 20, 5, 2, 2, act="relu") + + self._simple_img_conv_pool_2 = SimpleImgConvPool( + self.full_name(), 20, 50, 5, 2, 2, act="relu") + + pool_2_shape = 50 * 4 * 4 + SIZE = 10 + scale = (2.0 / (pool_2_shape**2 * SIZE))**0.5 + self._fc = FC(self.full_name(), + 10, + param_attr=fluid.param_attr.ParamAttr( + initializer=fluid.initializer.NormalInitializer( + loc=0.0, scale=scale)), + act="softmax") + + def forward(self, inputs): + x = self._simple_img_conv_pool_1(inputs) + x = self._simple_img_conv_pool_2(x) + x = self._fc(x) + return x + + + + +4. 在`fluid.dygraph.guard()`中定义配置好的`MNIST`网络结构,此时即使没有训练也可以在`fluid.dygraph.guard()`中调用模型并且检查输出: + + with fluid.dygraph.guard(): + mnist = MNIST("mnist") + id, data = list(enumerate(train_reader()))[0] + dy_x_data = np.array( + [x[0].reshape(1, 28, 28) + for x in data]).astype('float32') + img = to_variable(dy_x_data) + print("cost is: {}".format(mnist(img).numpy())) + + + + cost is: [[0.10135901 0.1051138 0.1027941 ... 0.0972859 0.10221873 0.10165327] + [0.09735426 0.09970362 0.10198303 ... 0.10134517 0.10179105 0.10025002] + [0.09539858 0.10213123 0.09543551 ... 0.10613529 0.10535969 0.097991 ] + ... + [0.10120598 0.0996111 0.10512722 ... 0.10067689 0.10088114 0.10071224] + [0.09889644 0.10033772 0.10151272 ... 0.10245881 0.09878646 0.101483 ] + [0.09097178 0.10078511 0.10198414 ... 0.10317434 0.10087223 0.09816764]] + + Process finished with exit code 0 + +5. 构建训练循环,在每一轮参数更新完成后我们调用`mnist.clear_gradients()`来重置梯度: + + for epoch in range(epoch_num): + for batch_id, data in enumerate(train_reader()): + dy_x_data = np.array( + [x[0].reshape(1, 28, 28) + for x in data]).astype('float32') + y_data = np.array( + [x[1] for x in data]).astype('int64').reshape(BATCH_SIZE, 1) + + img = to_variable(dy_x_data) + label = to_variable(y_data) + label.stop_gradient = True + + cost = mnist(img) + loss = fluid.layers.cross_entropy(cost, label) + avg_loss = fluid.layers.mean(loss) + + dy_out = avg_loss.numpy() + avg_loss.backward() + sgd.minimize(avg_loss) + mnist.clear_gradients() + + + + +6. 变量及优化器 + + 模型的参数或者任何您希望检测的值可以作为变量封装在类中,并且通过对象获取并使用`numpy()`方法获取其`ndarray`的输出, 在训练过程中您可以使用`mnist.parameters()`来获取到网络中所有的参数,也可以指定某一个`Layer`的某个参数或者`parameters()`来获取该层的所有参数,使用`numpy()`方法随时查看参数的值 + + 反向运行后调用之前定义的`SGD`优化器对象的`minimize`方法进行参数更新: + + with fluid.dygraph.guard(): + fluid.default_startup_program().random_seed = seed + fluid.default_main_program().random_seed = seed + + mnist = MNIST("mnist") + sgd = SGDOptimizer(learning_rate=1e-3) + train_reader = paddle.batch( + paddle.dataset.mnist.train(), batch_size= BATCH_SIZE, drop_last=True) + + dy_param_init_value = {} + np.set_printoptions(precision=3, suppress=True) + for epoch in range(epoch_num): + for batch_id, data in enumerate(train_reader()): + dy_x_data = np.array( + [x[0].reshape(1, 28, 28) + for x in data]).astype('float32') + y_data = np.array( + [x[1] for x in data]).astype('int64').reshape(BATCH_SIZE, 1) + + img = to_variable(dy_x_data) + label = to_variable(y_data) + label.stop_gradient = True + + cost = mnist(img) + loss = fluid.layers.cross_entropy(cost, label) + avg_loss = fluid.layers.mean(loss) + + dy_out = avg_loss.numpy() + + if epoch == 0 and batch_id == 0: + for param in mnist.parameters(): + dy_param_init_value[param.name] = param.numpy() + + avg_loss.backward() + sgd.minimize(avg_loss) + mnist.clear_gradients() + + dy_param_value = {} + for param in mnist.parameters(): + dy_param_value[param.name] = param.numpy() + + if batch_id % 20 == 0: + print("Loss at step {}: {:.7}".format(batch_id, avg_loss.numpy())) + print("Final loss: {:.7}".format(avg_loss.numpy())) + print("_simple_img_conv_pool_1_conv2d W's mean is: {}".format(mnist._simple_img_conv_pool_1._conv2d._filter_param.numpy().mean())) + print("_simple_img_conv_pool_1_conv2d Bias's mean is: {}".format(mnist._simple_img_conv_pool_1._conv2d._bias_param.numpy().mean())) + + + + + Loss at step 0: [2.302] + Loss at step 20: [1.616] + Loss at step 40: [1.244] + Loss at step 60: [1.142] + Loss at step 80: [0.911] + Loss at step 100: [0.824] + Loss at step 120: [0.774] + Loss at step 140: [0.626] + Loss at step 160: [0.609] + Loss at step 180: [0.627] + Loss at step 200: [0.466] + Loss at step 220: [0.499] + Loss at step 240: [0.614] + Loss at step 260: [0.585] + Loss at step 280: [0.503] + Loss at step 300: [0.423] + Loss at step 320: [0.509] + Loss at step 340: [0.348] + Loss at step 360: [0.452] + Loss at step 380: [0.397] + Loss at step 400: [0.54] + Loss at step 420: [0.341] + Loss at step 440: [0.337] + Loss at step 460: [0.155] + Final loss: [0.164] + _simple_img_conv_pool_1_conv2d W's mean is: 0.00606656912714 + _simple_img_conv_pool_1_conv2d Bias's mean is: -3.4576318285e-05 + +7. 性能 + + 在使用`fluid.dygraph.guard()`可以通过传入`fluid.CUDAPlace(0)`或者`fluid.CPUPlace()`来选择执行DyGraph的设备,通常如果不做任何处理将会自动适配您的设备。 + +## 模型参数的保存 + +
在模型训练中可以使用` fluid.dygraph.save_persistables(your_model_object.state_dict(), "save_dir")`来保存`your_model_object`中所有的模型参数。也可以自定义需要保存的“参数名” - “参数对象”的Python Dictionary传入。 + +同样可以使用`your_modle_object.load_dict( + fluid.dygraph.load_persistables(your_model_object.state_dict(), "save_dir"))`接口来恢复保存的模型参数从而达到继续训练的目的。 + +下面的代码展示了如何在“手写数字识别”任务中保存参数并且读取已经保存的参数来继续训练。 + + for epoch in range(epoch_num): + for batch_id, data in enumerate(train_reader()): + dy_x_data = np.array( + [x[0].reshape(1, 28, 28) + for x in data]).astype('float32') + y_data = np.array( + [x[1] for x in data]).astype('int64').reshape(BATCH_SIZE, 1) + + img = to_variable(dy_x_data) + label = to_variable(y_data) + label.stop_gradient = True + + cost = mnist(img) + loss = fluid.layers.cross_entropy(cost, label) + avg_loss = fluid.layers.mean(loss) + + dy_out = avg_loss.numpy() + + avg_loss.backward() + sgd.minimize(avg_loss) + fluid.dygraph.save_persistables(mnist.state_dict(), "save_dir") + mnist.clear_gradients() + + for param in mnist.parameters(): + dy_param_init_value[param.name] = param.numpy() + + mnist.load_dict(fluid.dygraph.load_persistables(mnist.state_dict(), "save_dir")) + restore = mnist.parameters() + # check save and load + success = True + for value in restore: + if (not np.allclose(value.numpy(), dy_param_init_value[value.name])) or (not np.isfinite(value.numpy().all())) or (np.isnan(value.numpy().any())): + success = False + print("model save and load success? {}".format(success)) + + + + +## 模型评估 + +当我们需要在DyGraph模式下利用搭建的模型进行预测任务,可以使用`YourModel.eval()`接口,在之前的手写数字识别模型中我们使用`mnist.eval()`来启动预测模式(我们默认在`fluid.dygraph.guard()`上下文中是训练模式),在预测的模式下,DyGraph将只会执行前向的预测网络,而不会进行自动求导并执行反向网络: + +下面的代码展示了如何使用DyGraph模式训练一个用于执行“手写数字识别”任务的模型并保存,并且利用已经保存好的模型进行预测。 + +我们在第一个`fluid.dygraph.guard()`上下文中进行了模型的保存和训练,值得注意的是,当我们需要在训练的过程中进行预测时需要使用`YourModel.eval()`切换到预测模式,并且在预测完成后使用`YourModel.train()`切换回训练模式继续训练。 + +我们在第二个`fluid.dygraph.guard()`上下文中利用之前保存的`checkpoint`进行预测,同样的在执行预测前需要使用`YourModel.eval()`来切换的预测模式。 + + with fluid.dygraph.guard(): + fluid.default_startup_program().random_seed = seed + fluid.default_main_program().random_seed = seed + + mnist = MNIST("mnist") + adam = AdamOptimizer(learning_rate=0.001) + train_reader = paddle.batch( + paddle.dataset.mnist.train(), batch_size=BATCH_SIZE, drop_last=True) + test_reader = paddle.batch( + paddle.dataset.mnist.test(), batch_size=BATCH_SIZE, drop_last=True) + for epoch in range(epoch_num): + for batch_id, data in enumerate(train_reader()): + dy_x_data = np.array( + [x[0].reshape(1, 28, 28) + for x in data]).astype('float32') + y_data = np.array( + [x[1] for x in data]).astype('int64').reshape(BATCH_SIZE, 1) + + img = to_variable(dy_x_data) + label = to_variable(y_data) + label.stop_gradient = True + + cost, acc = mnist(img, label) + + loss = fluid.layers.cross_entropy(cost, label) + avg_loss = fluid.layers.mean(loss) + avg_loss.backward() + adam.minimize(avg_loss) + # save checkpoint + mnist.clear_gradients() + if batch_id % 100 == 0: + print("Loss at epoch {} step {}: {:}".format(epoch, batch_id, avg_loss.numpy())) + mnist.eval() + test_cost, test_acc = self._test_train(test_reader, mnist, BATCH_SIZE) + mnist.train() + print("Loss at epoch {} , Test avg_loss is: {}, acc is: {}".format(epoch, test_cost, test_acc)) + + fluid.dygraph.save_persistables(mnist.state_dict(), "save_dir") + print("checkpoint saved") + + with fluid.dygraph.guard(): + fluid.default_startup_program().random_seed = seed + fluid.default_main_program().random_seed = seed + + mnist_infer = MNIST("mnist") + # load checkpoint + mnist_infer.load_dict( + fluid.dygraph.load_persistables(mnist.state_dict(), "save_dir")) + print("checkpoint loaded") + + # start evaluate mode + mnist_infer.eval() + def load_image(file): + im = Image.open(file).convert('L') + im = im.resize((28, 28), Image.ANTIALIAS) + im = np.array(im).reshape(1, 1, 28, 28).astype(np.float32) + im = im / 255.0 * 2.0 - 1.0 + return im + + cur_dir = os.path.dirname(os.path.realpath(__file__)) + tensor_img = load_image(cur_dir + '/image/infer_3.png') + + results = mnist_infer(to_variable(tensor_img)) + lab = np.argsort(results.numpy()) + print("Inference result of image/infer_3.png is: %d" % lab[0][-1]) + + + + + Loss at epoch 3 , Test avg_loss is: 0.0721620170576, acc is: 0.97796474359 + Loss at epoch 4 step 0: [0.01078923] + Loss at epoch 4 step 100: [0.10447877] + Loss at epoch 4 step 200: [0.05149534] + Loss at epoch 4 step 300: [0.0122997] + Loss at epoch 4 step 400: [0.0281883] + Loss at epoch 4 step 500: [0.10709661] + Loss at epoch 4 step 600: [0.1306036] + Loss at epoch 4 step 700: [0.01628026] + Loss at epoch 4 step 800: [0.07947419] + Loss at epoch 4 step 900: [0.02067161] + Loss at epoch 4 , Test avg_loss is: 0.0802323290939, acc is: 0.976963141026 + checkpoint saved + checkpoint loaded + + + Ran 1 test in 208.017s + + Inference result of image/infer_3.png is: 3 + + +## 编写兼容的模型 + +以上一步中手写数字识别的例子为例,相同的模型代码可以直接在PaddlePaddle的`Executor`中执行: + + exe = fluid.Executor(fluid.CPUPlace( + ) if not core.is_compiled_with_cuda() else fluid.CUDAPlace(0)) + + mnist = MNIST("mnist") + sgd = SGDOptimizer(learning_rate=1e-3) + train_reader = paddle.batch( + paddle.dataset.mnist.train(), batch_size= BATCH_SIZE, drop_last=True) + + img = fluid.layers.data( + name='pixel', shape=[1, 28, 28], dtype='float32') + label = fluid.layers.data(name='label', shape=[1], dtype='int64') + cost = mnist(img) + loss = fluid.layers.cross_entropy(cost, label) + avg_loss = fluid.layers.mean(loss) + sgd.minimize(avg_loss) + + # initialize params and fetch them + static_param_init_value = {} + static_param_name_list = [] + for param in mnist.parameters(): + static_param_name_list.append(param.name) + + out = exe.run(fluid.default_startup_program(), + fetch_list=static_param_name_list) + + for i in range(len(static_param_name_list)): + static_param_init_value[static_param_name_list[i]] = out[i] + + for epoch in range(epoch_num): + for batch_id, data in enumerate(train_reader()): + static_x_data = np.array( + [x[0].reshape(1, 28, 28) + for x in data]).astype('float32') + y_data = np.array( + [x[1] for x in data]).astype('int64').reshape([BATCH_SIZE, 1]) + + fetch_list = [avg_loss.name] + fetch_list.extend(static_param_name_list) + out = exe.run( + fluid.default_main_program(), + feed={"pixel": static_x_data, + "label": y_data}, + fetch_list=fetch_list) + + static_param_value = {} + static_out = out[0] + for i in range(1, len(out)): + static_param_value[static_param_name_list[i - 1]] = out[ + i] + + + diff --git a/doc/fluid/user_guides/index_cn.rst b/doc/fluid/user_guides/index_cn.rst index ed44aea6d0cb387863b37509fe470c3e4f106fbe..c64a97f166866009d506503186ac40524fe6b189 100644 --- a/doc/fluid/user_guides/index_cn.rst +++ b/doc/fluid/user_guides/index_cn.rst @@ -14,6 +14,9 @@ - `训练神经网络 <../user_guides/howto/training/index_cn.html>`_:介绍如何使用 Fluid 进行单机训练、多机训练、以及保存和载入模型变量 + + - `DyGraph模式 <../user_guides/howto/dygraph/DyGraph.md>`_:介绍在 Fluid 下使用DyGraph + - `模型评估与调试 <../user_guides/howto/evaluation_and_debugging/index_cn.html>`_:介绍在 Fluid 下进行模型评估和调试的方法,包括: 基于 Fluid 复现的多领域经典模型: @@ -28,4 +31,5 @@ howto/configure_simple_model/index_cn.rst howto/training/index_cn.rst howto/evaluation_and_debugging/index_cn.rst + howto/dygraph/DyGraph.md models/index_cn.rst