什么是人工神经网络(ANN)?
你有没有想过你的大脑如何识别某物?让我们说你看一只猫的图片,你的大脑立即告诉你它是一只猫。而酷的部分是你甚至从未意识到你的大脑是如何工作的。
如果你没有从石器时代传送,我想你可能听说过机器学习。
因此,在本文中,我将解释特定类型的机器学习,称为神经网络。
首先要说的是:什么是神经网络?
神经网络是一种受人脑启发的计算机机器学习模型。最近神经网络在Google的深度学习征服最佳Alpha Go播放器后获得了普及。
最好的部分是没有人参与,机器学会了自己玩Alpha Go。
在神经网络中,基本单位是神经元,而神经网络(人工神经网络)是其感知器。感知器可以采用尽可能多的输入并将其输出作为输入提供给多个神经元。从而创建一个神经元网络。
感知器是由科学家弗兰克罗森布拉特在20世纪50年代和60年代开发的,受到沃伦麦卡洛克和沃尔特皮茨的早期工作的启发。
单个感知器如下所示:

单感知器
这些神经元或感知器有许多配置; 他们连接的方式形成神经网络的不同模型,如深度神经网络,回归神经网络等......
神经网络由以下组件组成
输入层,x
任意数量的隐藏层
输出层,ŷ
每层之间的一组权重和偏差,W和b
每个隐藏层的激活函数的选择,σ。在本教程中,我们将使用Sigmoid激活函数。
神经网络如何计算事物。
神经元通过将所有输入的乘积与权重相加然后将其作为输出来计算。
然后将该输出提供给激活函数,并且激活函数的输出是由中子提供的最终输出。
激活功能只是一个阈值函数,它将输出映射到指定范围。
因此输出映射到阈值限制之间的值。
神经网络调整/学习的唯一内容是权重。在训练神经网络的同时调整权重。
然后将输出提供给激活函数,在激活函数之后,我们得到最终输出。
标记单层神经网络
在此示例中,使用的激活函数是sigmoid函数。但是,您可以选择许多激活功能,如ReLU,SoftMax,TanH等......
每个都有不同的目的,有自己的优点和缺点。
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