hanbt / learn_dl

Deep learning algorithms source code for beginners
Apache License 2.0
1.2k stars 988 forks source link

感谢分享,请问有Python3版的吗 #22

Open jayboxyz opened 6 years ago

liukunr commented 6 years ago
#!/usr/bin/env python
# -*- coding: UTF-8 -*-
from functools import reduce

class Perceptron(object):
    def __init__(self, input_num, activator):
        '''
        初始化感知器,设置输入参数的个数,以及激活函数。
        激活函数的类型为double -> double
        '''
        self.activator = activator
        # 权重向量初始化为0
        self.weights = [0.0 for _ in range(input_num)]
        # 偏置项初始化为0
        self.bias = 0.0

    def __str__(self):
        '''
        打印学习到的权重、偏置项
        '''
        return 'weights\t:%s\nbias\t:%f\n' % (self.weights, self.bias)

    def predict(self, input_vec):
        '''
        输入向量,输出感知器的计算结果
        '''
        # 把input_vec[x1,x2,x3...]和weights[w1,w2,w3,...]打包在一起
        # 变成[(x1,w1),(x2,w2),(x3,w3),...]
        # 然后利用map函数计算[x1*w1, x2*w2, x3*w3]
        # 最后利用reduce求和
        return self.activator(
            reduce(lambda a, b: a + b,
                   map(lambda xw: xw[0] * xw[1],  
                       zip(input_vec, self.weights))
                , 0.0) + self.bias)

    def train(self, input_vecs, labels, iteration, rate):
        '''
        输入训练数据:一组向量、与每个向量对应的label;以及训练轮数、学习率
        '''
        for i in range(iteration):
            self._one_iteration(input_vecs, labels, rate)

    def _one_iteration(self, input_vecs, labels, rate):
        '''
        一次迭代,把所有的训练数据过一遍
        '''
        # 把输入和输出打包在一起,成为样本的列表[(input_vec, label), ...]
        # 而每个训练样本是(input_vec, label)
        samples = zip(input_vecs, labels)
        # 对每个样本,按照感知器规则更新权重
        for (input_vec, label) in samples:
            # 计算感知器在当前权重下的输出
            output = self.predict(input_vec)
            # 更新权重
            self._update_weights(input_vec, output, label, rate)

    def _update_weights(self, input_vec, output, label, rate):
        '''
        按照感知器规则更新权重
        '''
        # 把input_vec[x1,x2,x3,...]和weights[w1,w2,w3,...]打包在一起
        # 变成[(x1,w1),(x2,w2),(x3,w3),...]
        # 然后利用感知器规则更新权重
        delta = label - output
        self.weights = list(map(
            lambda xw: xw[1] + rate * delta * xw[0],
            zip(input_vec, self.weights)))
        # 更新bias
        self.bias += rate * delta

def f(x):
    '''
    定义激活函数f
    '''
    return 1 if x > 0 else 0

def get_training_dataset():
    '''
    基于and真值表构建训练数据
    '''
    # 构建训练数据
    # 输入向量列表
    input_vecs = [[1,1], [0,0], [1,0], [0,1]]
    # 期望的输出列表,注意要与输入一一对应
    # [1,1] -> 1, [0,0] -> 0, [1,0] -> 0, [0,1] -> 0
    labels = [1, 0, 0, 0]
    return input_vecs, labels    

def train_and_perceptron():
    '''
    使用and真值表训练感知器
    '''
    # 创建感知器,输入参数个数为2(因为and是二元函数),激活函数为f
    p = Perceptron(2, f)
    # 训练,迭代10轮, 学习速率为0.1
    input_vecs, labels = get_training_dataset()
    p.train(input_vecs, labels, 10, 0.1)
    #返回训练好的感知器
    return p

if __name__ == '__main__': 
    # 训练and感知器
    and_perception = train_and_perceptron()
    # 打印训练获得的权重
    print(and_perception)
    # 测试
    print('1 and 1 = %d' % and_perception.predict([1, 1]))
    print('0 and 0 = %d' % and_perception.predict([0, 0]))
    print('1 and 0 = %d' % and_perception.predict([1, 0]))
    print('0 and 1 = %d' % and_perception.predict([0, 1]))
Danielyan86 commented 6 years ago

@strivebo 用py3对部分代码做了重构,欢迎讨论 https://github.com/Danielyan86/learn_dl/tree/master/python3