拉扎涅神经网络层中的偏差

Question

我想知道是否有一种方式来增加偏置节点到每一层的拉桑尼神经网络工具包？我一直试图在文件中找到相关的信息。

这是我建立的网络，但我不知道如何在每个层中添加一个偏置节点。

def build_mlp(input_var=None):
    # This creates an MLP of two hidden layers of 800 units each, followed by
    # a softmax output layer of 10 units. It applies 20% dropout to the input
    # data and 50% dropout to the hidden layers.

    # Input layer, specifying the expected input shape of the network
    # (unspecified batchsize, 1 channel, 28 rows and 28 columns) and
    # linking it to the given Theano variable `input_var`, if any:
    l_in = lasagne.layers.InputLayer(shape=(None, 60),
                                     input_var=input_var)

    # Apply 20% dropout to the input data:
    l_in_drop = lasagne.layers.DropoutLayer(l_in, p=0.2)

    # Add a fully-connected layer of 800 units, using the linear rectifier, and
    # initializing weights with Glorot's scheme (which is the default anyway):
    l_hid1 = lasagne.layers.DenseLayer(
            l_in_drop, num_units=800,
            nonlinearity=lasagne.nonlinearities.rectify,
            W=lasagne.init.Uniform())

    # We'll now add dropout of 50%:
    l_hid1_drop = lasagne.layers.DropoutLayer(l_hid1, p=0.5)

    # Another 800-unit layer:
    l_hid2 = lasagne.layers.DenseLayer(
            l_hid1_drop, num_units=800,
            nonlinearity=lasagne.nonlinearities.rectify)

    # 50% dropout again:
    l_hid2_drop = lasagne.layers.DropoutLayer(l_hid2, p=0.5)

    # Finally, we'll add the fully-connected output layer, of 10 softmax units:
    l_out = lasagne.layers.DenseLayer(
            l_hid2_drop, num_units=2,
            nonlinearity=lasagne.nonlinearities.softmax)

    # Each layer is linked to its incoming layer(s), so we only need to pass
    # the output layer to give access to a network in Lasagne:
    return l_out

Answer 1

实际上，您不必显式地创建偏差，因为DenseLayer()和卷积基层也有一个默认的关键字参数：

b=lasagne.init.Constant(0.)。

因此，如果不希望具有显式传递bias，则可以避免创建bias=None，但情况并非如此。

因此，简单地说，您确实有偏差参数，而不将None传递给bias参数，例如：

hidden = Denselayer(...bias=None)