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吴恩达《深度学习》-课后测验-第一门课 (Neural Networks and Deep Learning)-Week 4 - Key concepts on Deep Neural Networks(第四周 测验 – 深层神经网络)

时间:2019-12-16 11:41:45      阅读:167      评论:0      收藏:0      [点我收藏+]

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Week 4 Quiz - Key concepts on Deep Neural Networks(第四周 测验 – 深层神经网络)

\1. What is the “cache” used for in our implementation of forward propagation and backward propagation?(在实现前向传播和反向传播中使用的“cache”是什么?)

【 】It is used to cache the intermediate values of the cost function during training.(用于在训练期间缓存成本函数的中间值。)

【 】We use it to pass variables computed during forward propagation to the corresponding backward propagation step. It contains useful values for backward propagation to compute derivatives.(我们用它传递前向传播中计算的变量到相应的反向传播步骤,它包含用于计算导数的反向传播的有用值。)

【 】It is used to keep track of the hyperparameters that we are searching over, to speed up computation.(它用于跟踪我们正在搜索的超参数,以加速计算。)

【 】We use it to pass variables computed during backward propagation to the corresponding forward propagation step. It contains useful values for forward propagation to compute activations.(我们使用它将向后传播计算的变量传递给相应的正向传播步骤,它包含用于计算计算激活的正向传播的有用值。)

答案

【★】We use it to pass variables computed during forward propagation to the corresponding backward propagation step. It contains useful values for backward propagation to compute derivatives.(我们用它传递前向传播中计算的变量到相应的反向传播步骤,它包含用于计算导数的反向传播的有用值。)

Note: the “cache” records values from the forward propagation units and sends it to the backward propagation units because it is needed to compute the chain rule derivatives.(请注意:“cache”记录来自正向传播单元的值并将其发送到反向传播单元,因为需要链式计算导数。)

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\2. Among the following, which ones are “hyperparameters”? (Check all that apply.)(以下哪些是“超参数”?)

【 】size of the hidden layers \(??^{[??]}\) (隐藏层的大小\(??^{[??]}\))

【 】learning rate α(学习率 α)

【 】number of iterations(迭代次数)

【 】number of layers ?? in the neural network(神经网络中的层数??)

答案

全对

Note: You can check this Quora post or this blog post.(请注意:你可以查看 Quora 的这篇文章 或者 这篇博客.)

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\3. Which of the following statements is true?(下列哪个说法是正确的?)

【 】The deeper layers of a neural network are typically computing more complex features of the input than the earlier layers. (神经网络的更深层通常比前面的层计算更复杂的输入特征。) 【 】 The earlier layers of a neural network are typically computing more complex features of the input than the deeper layers.(神经网络的前面的层通常比更深层计算更复杂的输入特征。)

答案

【★】The deeper layers of a neural network are typically computing more complex features of the input than the earlier layers. (神经网络的更深层通常比前面的层计算更复杂的输入特征。)

Note: You can check the lecture videos. I think Andrew used a CNN example to explain this.(注意:您 可以查看视频,我想用吴恩达的用美国有线电视新闻网的例子来解释这个。)

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\4. Vectorization allows you to compute forward propagation in an ??-layer neural network without an explicit for-loop (or any other explicit iterative loop) over the layers l=1, 2, …,L. True/False?(向量化允许您在??层神经网络中计算前向传播,而不需要在层(l = 1,2,…,L)上显式的使用 for-loop(或任何其他显式迭代循环),正确吗?)

【 】 True(正确) 【 】 False(错误)

答案

【★】 False(错误)

Note: We cannot avoid the for-loop iteration over the computations among layers.(请注意:在层间 计算中,我们不能避免 for 循环迭代。)

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\5. Assume we store the values for \(??^{[??]}\) in an array called layers, as follows: layer_dims = \([??_??, 4,3,2,1]\). So layer 1 has four hidden units, layer 2 has 3 hidden units and so on. Which of the following for-loops will allow you to initialize the parameters for the model?(假设我们将 \(??^{[??]}\)的值存储在名为 layers 的数组中,如下所示:layer_dims =\([??_??, 4,3,2,1]\)。 因此,第 1 层有四个隐藏单元,第 2 层有三个隐藏单元,依此类推。您可以使用哪个 for 循环初始化模型参 数?)

答案

for(i in range(1, len(layer_dims))):
    parameter[‘W’ + str(i)] = np.random.randn(layers[i], layers[i- 1])) * 0.01
    parameter[‘b’ + str(i)] = np.random.randn(layers[i], 1) * 0.01

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\6. Consider the following neural network.(下面关于神经网络的说法正确的是:)

技术图片

【 】The number of layers?? is 4. The number of hidden layers is 3.(层数??为 4,隐藏层数为 3)

答案

显然

Note: The input layer (?? [0] ) does not count.(注意:输入层(?? [0])不计数。)
As seen in lecture, the number of layers is counted as the number of hidden layers + 1. The input and output layers are not counted as hidden layers.(正如视频中所看到的那样,层数被计为隐藏层数 +1。输入层和输出层不计为隐藏层。)

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\7. During forward propagation, in the forward function for a layer ?? you need to know what is the activation function in a layer (Sigmoid, tanh, ReLU, etc.). During backpropagation, the corresponding backward function also needs to know what is the activation function for layer ??, since the gradient depends on it. True/False?(在前向传播期间,在层??的前向传播函数中, 您需要知道层??中的激活函数(Sigmoid,tanh,ReLU 等)是什么, 在反向传播期间,相应 的反向传播函数也需要知道第??层的激活函数是什么,因为梯度是根据它来计算的,正确吗?)

【 】 True(正确) 【 】False(错误)

答案

True(正确)

Note: During backpropagation you need to know which activation was used in the forward propagation to be able to compute the correct derivative.(注:在反向传播期间,您需要知道正向传播中使用哪种激活函数才能计算正确的导数。)

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8.There are certain functions with the following properties:(有一些函数具有以下属性:)

(i) To compute the function using a shallow network circuit, you will need a large network (where we measure size by the number of logic gates in the network), but (ii) To compute it using a deep network circuit, you need only an exponentially smaller network. True/False?((i) 使用浅网络电路计算函数时,需要一个大网络(我们通过网络中的逻辑门数量来度量大小), 但是(ii)使用深网络电路来计算它,只需要一个指数较小的网络。真/假?)

【 】True(正确) 【 】False(错误)

答案

True

Note: See lectures, exactly same idea was explained.(参见视频,完全相同的题。)

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\9. Consider the following 2 hidden layer neural network: Which of the following statements are True? (Check all that apply).((在 2 层隐层神经网络中,下列哪个说法是正确的?只列出了正 确选项))

【 】\(??^{[1]}\) will have shape (4, 4)(\(??^{[1]}\)的维度为 (4, 4))

【 】\(??^{[1]}\) will have shape (4, 1)(\(??^{[1]}\)的维度为 (4, 1))

【 】\(??^{[2]}\) will have shape (3, 4)(\(??^{[2]}\)的维度为 (3, 4))

【 】\(??^{[2]}\) will have shape (3, 1)(\(??^{[2]}\)的维度为 (3, 1))

【 】\(??^{[3]}\) will have shape (1, 1)(\(??^{[3]}\)的维度为 (1, 1))

【 】\(??^{[3]}\) will have shape (1, 3)(\(??^{[3]}\)的维度为 (1, 3))

答案

Note: See [this image] for general formulas.(注:请参阅图片。)

技术图片

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\10. Whereas the previous question used a specific network, in the general case what is the dimension of \(??^{[1]}\) , the weight matrix associated with layer ???(前面的问题使用了一个特定的 网络,与层 ll 有关的权重矩阵在一般情况下,\(??^{[1]}\) 的维数是多少)

【 】\(??^{[1]}\) has shape (\(??^{[??]} ,??^{[???1]} )(??^{[1]}\)的维度是$ (??^{[??]} ,??^{[???1]} )$

答案

Note: See [this image] for general formulas.(注:请参阅图片。)

技术图片

吴恩达《深度学习》-课后测验-第一门课 (Neural Networks and Deep Learning)-Week 4 - Key concepts on Deep Neural Networks(第四周 测验 – 深层神经网络)

标签:work   model   ora   without   soc   次数   spec   hid   hat   

原文地址:https://www.cnblogs.com/phoenixash/p/12048137.html

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