【Python机器学习】实验04(1) 多分类(基于逻辑回归)实践

文章目录

  • 多分类以及机器学习实践
    • 如何对多个类别进行分类
      • 1.1 数据的预处理
      • 1.2 训练数据的准备
      • 1.3 定义假设函数,代价函数,梯度下降算法(从实验3复制过来)
      • 1.4 调用梯度下降算法来学习三个分类模型的参数
      • 1.5 利用模型进行预测
      • 1.6 评估模型
      • 1.7 试试sklearn
    • 实验4(1) 请动手完成你们第一个多分类问题,祝好运!完成下面代码
      • 2.1 数据读取
      • 2.2 训练数据的准备
      • 2.3 定义假设函数、代价函数和梯度下降算法
      • 2.4 学习这四个分类模型
      • 2.5 利用模型进行预测
      • 2.6 计算准确率

多分类以及机器学习实践

如何对多个类别进行分类

Iris数据集是常用的分类实验数据集,由Fisher, 1936收集整理。Iris也称鸢尾花卉数据集,是一类多重变量分析的数据集。数据集包含150个数据样本,分为3类,每类50个数据,每个数据包含4个属性。可通过花萼长度,花萼宽度,花瓣长度,花瓣宽度4个属性预测鸢尾花卉属于(Setosa,Versicolour,Virginica)三个种类中的哪一类。

iris以鸢尾花的特征作为数据来源,常用在分类操作中。该数据集由3种不同类型的鸢尾花的各50个样本数据构成。其中的一个种类与另外两个种类是线性可分离的,后两个种类是非线性可分离的。

该数据集包含了4个属性:
Sepal.Length(花萼长度),单位是cm;
Sepal.Width(花萼宽度),单位是cm;
Petal.Length(花瓣长度),单位是cm;
Petal.Width(花瓣宽度),单位是cm;

种类:Iris Setosa(山鸢尾)、Iris Versicolour(杂色鸢尾),以及Iris Virginica(维吉尼亚鸢尾)。

1.1 数据的预处理

import sklearn.datasets as datasets
import pandas as pd
import numpy as np
data=datasets.load_iris()
data
{'data': array([[5.1, 3.5, 1.4, 0.2],
        [4.9, 3. , 1.4, 0.2],
        [4.7, 3.2, 1.3, 0.2],
        [4.6, 3.1, 1.5, 0.2],
        [5. , 3.6, 1.4, 0.2],
        [5.4, 3.9, 1.7, 0.4],
        [4.6, 3.4, 1.4, 0.3],
        [5. , 3.4, 1.5, 0.2],
        [4.4, 2.9, 1.4, 0.2],
        [4.9, 3.1, 1.5, 0.1],
        [5.4, 3.7, 1.5, 0.2],
        [4.8, 3.4, 1.6, 0.2],
        [4.8, 3. , 1.4, 0.1],
        [4.3, 3. , 1.1, 0.1],
        [5.8, 4. , 1.2, 0.2],
        [5.7, 4.4, 1.5, 0.4],
        [5.4, 3.9, 1.3, 0.4],
        [5.1, 3.5, 1.4, 0.3],
        [5.7, 3.8, 1.7, 0.3],
        [5.1, 3.8, 1.5, 0.3],
        [5.4, 3.4, 1.7, 0.2],
        [5.1, 3.7, 1.5, 0.4],
        [4.6, 3.6, 1. , 0.2],
        [5.1, 3.3, 1.7, 0.5],
        [4.8, 3.4, 1.9, 0.2],
        [5. , 3. , 1.6, 0.2],
        [5. , 3.4, 1.6, 0.4],
        [5.2, 3.5, 1.5, 0.2],
        [5.2, 3.4, 1.4, 0.2],
        [4.7, 3.2, 1.6, 0.2],
        [4.8, 3.1, 1.6, 0.2],
        [5.4, 3.4, 1.5, 0.4],
        [5.2, 4.1, 1.5, 0.1],
        [5.5, 4.2, 1.4, 0.2],
        [4.9, 3.1, 1.5, 0.2],
        [5. , 3.2, 1.2, 0.2],
        [5.5, 3.5, 1.3, 0.2],
        [4.9, 3.6, 1.4, 0.1],
        [4.4, 3. , 1.3, 0.2],
        [5.1, 3.4, 1.5, 0.2],
        [5. , 3.5, 1.3, 0.3],
        [4.5, 2.3, 1.3, 0.3],
        [4.4, 3.2, 1.3, 0.2],
        [5. , 3.5, 1.6, 0.6],
        [5.1, 3.8, 1.9, 0.4],
        [4.8, 3. , 1.4, 0.3],
        [5.1, 3.8, 1.6, 0.2],
        [4.6, 3.2, 1.4, 0.2],
        [5.3, 3.7, 1.5, 0.2],
        [5. , 3.3, 1.4, 0.2],
        [7. , 3.2, 4.7, 1.4],
        [6.4, 3.2, 4.5, 1.5],
        [6.9, 3.1, 4.9, 1.5],
        [5.5, 2.3, 4. , 1.3],
        [6.5, 2.8, 4.6, 1.5],
        [5.7, 2.8, 4.5, 1.3],
        [6.3, 3.3, 4.7, 1.6],
        [4.9, 2.4, 3.3, 1. ],
        [6.6, 2.9, 4.6, 1.3],
        [5.2, 2.7, 3.9, 1.4],
        [5. , 2. , 3.5, 1. ],
        [5.9, 3. , 4.2, 1.5],
        [6. , 2.2, 4. , 1. ],
        [6.1, 2.9, 4.7, 1.4],
        [5.6, 2.9, 3.6, 1.3],
        [6.7, 3.1, 4.4, 1.4],
        [5.6, 3. , 4.5, 1.5],
        [5.8, 2.7, 4.1, 1. ],
        [6.2, 2.2, 4.5, 1.5],
        [5.6, 2.5, 3.9, 1.1],
        [5.9, 3.2, 4.8, 1.8],
        [6.1, 2.8, 4. , 1.3],
        [6.3, 2.5, 4.9, 1.5],
        [6.1, 2.8, 4.7, 1.2],
        [6.4, 2.9, 4.3, 1.3],
        [6.6, 3. , 4.4, 1.4],
        [6.8, 2.8, 4.8, 1.4],
        [6.7, 3. , 5. , 1.7],
        [6. , 2.9, 4.5, 1.5],
        [5.7, 2.6, 3.5, 1. ],
        [5.5, 2.4, 3.8, 1.1],
        [5.5, 2.4, 3.7, 1. ],
        [5.8, 2.7, 3.9, 1.2],
        [6. , 2.7, 5.1, 1.6],
        [5.4, 3. , 4.5, 1.5],
        [6. , 3.4, 4.5, 1.6],
        [6.7, 3.1, 4.7, 1.5],
        [6.3, 2.3, 4.4, 1.3],
        [5.6, 3. , 4.1, 1.3],
        [5.5, 2.5, 4. , 1.3],
        [5.5, 2.6, 4.4, 1.2],
        [6.1, 3. , 4.6, 1.4],
        [5.8, 2.6, 4. , 1.2],
        [5. , 2.3, 3.3, 1. ],
        [5.6, 2.7, 4.2, 1.3],
        [5.7, 3. , 4.2, 1.2],
        [5.7, 2.9, 4.2, 1.3],
        [6.2, 2.9, 4.3, 1.3],
        [5.1, 2.5, 3. , 1.1],
        [5.7, 2.8, 4.1, 1.3],
        [6.3, 3.3, 6. , 2.5],
        [5.8, 2.7, 5.1, 1.9],
        [7.1, 3. , 5.9, 2.1],
        [6.3, 2.9, 5.6, 1.8],
        [6.5, 3. , 5.8, 2.2],
        [7.6, 3. , 6.6, 2.1],
        [4.9, 2.5, 4.5, 1.7],
        [7.3, 2.9, 6.3, 1.8],
        [6.7, 2.5, 5.8, 1.8],
        [7.2, 3.6, 6.1, 2.5],
        [6.5, 3.2, 5.1, 2. ],
        [6.4, 2.7, 5.3, 1.9],
        [6.8, 3. , 5.5, 2.1],
        [5.7, 2.5, 5. , 2. ],
        [5.8, 2.8, 5.1, 2.4],
        [6.4, 3.2, 5.3, 2.3],
        [6.5, 3. , 5.5, 1.8],
        [7.7, 3.8, 6.7, 2.2],
        [7.7, 2.6, 6.9, 2.3],
        [6. , 2.2, 5. , 1.5],
        [6.9, 3.2, 5.7, 2.3],
        [5.6, 2.8, 4.9, 2. ],
        [7.7, 2.8, 6.7, 2. ],
        [6.3, 2.7, 4.9, 1.8],
        [6.7, 3.3, 5.7, 2.1],
        [7.2, 3.2, 6. , 1.8],
        [6.2, 2.8, 4.8, 1.8],
        [6.1, 3. , 4.9, 1.8],
        [6.4, 2.8, 5.6, 2.1],
        [7.2, 3. , 5.8, 1.6],
        [7.4, 2.8, 6.1, 1.9],
        [7.9, 3.8, 6.4, 2. ],
        [6.4, 2.8, 5.6, 2.2],
        [6.3, 2.8, 5.1, 1.5],
        [6.1, 2.6, 5.6, 1.4],
        [7.7, 3. , 6.1, 2.3],
        [6.3, 3.4, 5.6, 2.4],
        [6.4, 3.1, 5.5, 1.8],
        [6. , 3. , 4.8, 1.8],
        [6.9, 3.1, 5.4, 2.1],
        [6.7, 3.1, 5.6, 2.4],
        [6.9, 3.1, 5.1, 2.3],
        [5.8, 2.7, 5.1, 1.9],
        [6.8, 3.2, 5.9, 2.3],
        [6.7, 3.3, 5.7, 2.5],
        [6.7, 3. , 5.2, 2.3],
        [6.3, 2.5, 5. , 1.9],
        [6.5, 3. , 5.2, 2. ],
        [6.2, 3.4, 5.4, 2.3],
        [5.9, 3. , 5.1, 1.8]]),
 'target': array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
        2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
        2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2]),
 'frame': None,
 'target_names': array(['setosa', 'versicolor', 'virginica'], dtype='
data_x=data["data"]
data_y=data["target"]
data_x.shape,data_y.shape
((150, 4), (150,))
data_y=data_y.reshape([len(data_y),1])
data_y
array([[0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
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       [0],
       [0],
       [0],
       [0],
       [1],
       [1],
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       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
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       [2],
       [2],
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       [2],
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       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2]])
#法1 ,用拼接的方法
data=np.hstack([data_x,data_y])
#法二: 用插入的方法
np.insert(data_x,data_x.shape[1],data_y,axis=1)
array([[5.1, 3.5, 1.4, ..., 2. , 2. , 2. ],
       [4.9, 3. , 1.4, ..., 2. , 2. , 2. ],
       [4.7, 3.2, 1.3, ..., 2. , 2. , 2. ],
       ...,
       [6.5, 3. , 5.2, ..., 2. , 2. , 2. ],
       [6.2, 3.4, 5.4, ..., 2. , 2. , 2. ],
       [5.9, 3. , 5.1, ..., 2. , 2. , 2. ]])
data=pd.DataFrame(data,columns=["F1","F2","F3","F4","target"])
data
F1 F2 F3 F4 target
0 5.1 3.5 1.4 0.2 0.0
1 4.9 3.0 1.4 0.2 0.0
2 4.7 3.2 1.3 0.2 0.0
3 4.6 3.1 1.5 0.2 0.0
4 5.0 3.6 1.4 0.2 0.0
... ... ... ... ... ...
145 6.7 3.0 5.2 2.3 2.0
146 6.3 2.5 5.0 1.9 2.0
147 6.5 3.0 5.2 2.0 2.0
148 6.2 3.4 5.4 2.3 2.0
149 5.9 3.0 5.1 1.8 2.0

150 rows × 5 columns

data.insert(0,"ones",1)
data
ones F1 F2 F3 F4 target
0 1 5.1 3.5 1.4 0.2 0.0
1 1 4.9 3.0 1.4 0.2 0.0
2 1 4.7 3.2 1.3 0.2 0.0
3 1 4.6 3.1 1.5 0.2 0.0
4 1 5.0 3.6 1.4 0.2 0.0
... ... ... ... ... ... ...
145 1 6.7 3.0 5.2 2.3 2.0
146 1 6.3 2.5 5.0 1.9 2.0
147 1 6.5 3.0 5.2 2.0 2.0
148 1 6.2 3.4 5.4 2.3 2.0
149 1 5.9 3.0 5.1 1.8 2.0

150 rows × 6 columns

data["target"]=data["target"].astype("int32")
data
ones F1 F2 F3 F4 target
0 1 5.1 3.5 1.4 0.2 0
1 1 4.9 3.0 1.4 0.2 0
2 1 4.7 3.2 1.3 0.2 0
3 1 4.6 3.1 1.5 0.2 0
4 1 5.0 3.6 1.4 0.2 0
... ... ... ... ... ... ...
145 1 6.7 3.0 5.2 2.3 2
146 1 6.3 2.5 5.0 1.9 2
147 1 6.5 3.0 5.2 2.0 2
148 1 6.2 3.4 5.4 2.3 2
149 1 5.9 3.0 5.1 1.8 2

150 rows × 6 columns

1.2 训练数据的准备

data_x
array([[5.1, 3.5, 1.4, 0.2],
       [4.9, 3. , 1.4, 0.2],
       [4.7, 3.2, 1.3, 0.2],
       [4.6, 3.1, 1.5, 0.2],
       [5. , 3.6, 1.4, 0.2],
       [5.4, 3.9, 1.7, 0.4],
       [4.6, 3.4, 1.4, 0.3],
       [5. , 3.4, 1.5, 0.2],
       [4.4, 2.9, 1.4, 0.2],
       [4.9, 3.1, 1.5, 0.1],
       [5.4, 3.7, 1.5, 0.2],
       [4.8, 3.4, 1.6, 0.2],
       [4.8, 3. , 1.4, 0.1],
       [4.3, 3. , 1.1, 0.1],
       [5.8, 4. , 1.2, 0.2],
       [5.7, 4.4, 1.5, 0.4],
       [5.4, 3.9, 1.3, 0.4],
       [5.1, 3.5, 1.4, 0.3],
       [5.7, 3.8, 1.7, 0.3],
       [5.1, 3.8, 1.5, 0.3],
       [5.4, 3.4, 1.7, 0.2],
       [5.1, 3.7, 1.5, 0.4],
       [4.6, 3.6, 1. , 0.2],
       [5.1, 3.3, 1.7, 0.5],
       [4.8, 3.4, 1.9, 0.2],
       [5. , 3. , 1.6, 0.2],
       [5. , 3.4, 1.6, 0.4],
       [5.2, 3.5, 1.5, 0.2],
       [5.2, 3.4, 1.4, 0.2],
       [4.7, 3.2, 1.6, 0.2],
       [4.8, 3.1, 1.6, 0.2],
       [5.4, 3.4, 1.5, 0.4],
       [5.2, 4.1, 1.5, 0.1],
       [5.5, 4.2, 1.4, 0.2],
       [4.9, 3.1, 1.5, 0.2],
       [5. , 3.2, 1.2, 0.2],
       [5.5, 3.5, 1.3, 0.2],
       [4.9, 3.6, 1.4, 0.1],
       [4.4, 3. , 1.3, 0.2],
       [5.1, 3.4, 1.5, 0.2],
       [5. , 3.5, 1.3, 0.3],
       [4.5, 2.3, 1.3, 0.3],
       [4.4, 3.2, 1.3, 0.2],
       [5. , 3.5, 1.6, 0.6],
       [5.1, 3.8, 1.9, 0.4],
       [4.8, 3. , 1.4, 0.3],
       [5.1, 3.8, 1.6, 0.2],
       [4.6, 3.2, 1.4, 0.2],
       [5.3, 3.7, 1.5, 0.2],
       [5. , 3.3, 1.4, 0.2],
       [7. , 3.2, 4.7, 1.4],
       [6.4, 3.2, 4.5, 1.5],
       [6.9, 3.1, 4.9, 1.5],
       [5.5, 2.3, 4. , 1.3],
       [6.5, 2.8, 4.6, 1.5],
       [5.7, 2.8, 4.5, 1.3],
       [6.3, 3.3, 4.7, 1.6],
       [4.9, 2.4, 3.3, 1. ],
       [6.6, 2.9, 4.6, 1.3],
       [5.2, 2.7, 3.9, 1.4],
       [5. , 2. , 3.5, 1. ],
       [5.9, 3. , 4.2, 1.5],
       [6. , 2.2, 4. , 1. ],
       [6.1, 2.9, 4.7, 1.4],
       [5.6, 2.9, 3.6, 1.3],
       [6.7, 3.1, 4.4, 1.4],
       [5.6, 3. , 4.5, 1.5],
       [5.8, 2.7, 4.1, 1. ],
       [6.2, 2.2, 4.5, 1.5],
       [5.6, 2.5, 3.9, 1.1],
       [5.9, 3.2, 4.8, 1.8],
       [6.1, 2.8, 4. , 1.3],
       [6.3, 2.5, 4.9, 1.5],
       [6.1, 2.8, 4.7, 1.2],
       [6.4, 2.9, 4.3, 1.3],
       [6.6, 3. , 4.4, 1.4],
       [6.8, 2.8, 4.8, 1.4],
       [6.7, 3. , 5. , 1.7],
       [6. , 2.9, 4.5, 1.5],
       [5.7, 2.6, 3.5, 1. ],
       [5.5, 2.4, 3.8, 1.1],
       [5.5, 2.4, 3.7, 1. ],
       [5.8, 2.7, 3.9, 1.2],
       [6. , 2.7, 5.1, 1.6],
       [5.4, 3. , 4.5, 1.5],
       [6. , 3.4, 4.5, 1.6],
       [6.7, 3.1, 4.7, 1.5],
       [6.3, 2.3, 4.4, 1.3],
       [5.6, 3. , 4.1, 1.3],
       [5.5, 2.5, 4. , 1.3],
       [5.5, 2.6, 4.4, 1.2],
       [6.1, 3. , 4.6, 1.4],
       [5.8, 2.6, 4. , 1.2],
       [5. , 2.3, 3.3, 1. ],
       [5.6, 2.7, 4.2, 1.3],
       [5.7, 3. , 4.2, 1.2],
       [5.7, 2.9, 4.2, 1.3],
       [6.2, 2.9, 4.3, 1.3],
       [5.1, 2.5, 3. , 1.1],
       [5.7, 2.8, 4.1, 1.3],
       [6.3, 3.3, 6. , 2.5],
       [5.8, 2.7, 5.1, 1.9],
       [7.1, 3. , 5.9, 2.1],
       [6.3, 2.9, 5.6, 1.8],
       [6.5, 3. , 5.8, 2.2],
       [7.6, 3. , 6.6, 2.1],
       [4.9, 2.5, 4.5, 1.7],
       [7.3, 2.9, 6.3, 1.8],
       [6.7, 2.5, 5.8, 1.8],
       [7.2, 3.6, 6.1, 2.5],
       [6.5, 3.2, 5.1, 2. ],
       [6.4, 2.7, 5.3, 1.9],
       [6.8, 3. , 5.5, 2.1],
       [5.7, 2.5, 5. , 2. ],
       [5.8, 2.8, 5.1, 2.4],
       [6.4, 3.2, 5.3, 2.3],
       [6.5, 3. , 5.5, 1.8],
       [7.7, 3.8, 6.7, 2.2],
       [7.7, 2.6, 6.9, 2.3],
       [6. , 2.2, 5. , 1.5],
       [6.9, 3.2, 5.7, 2.3],
       [5.6, 2.8, 4.9, 2. ],
       [7.7, 2.8, 6.7, 2. ],
       [6.3, 2.7, 4.9, 1.8],
       [6.7, 3.3, 5.7, 2.1],
       [7.2, 3.2, 6. , 1.8],
       [6.2, 2.8, 4.8, 1.8],
       [6.1, 3. , 4.9, 1.8],
       [6.4, 2.8, 5.6, 2.1],
       [7.2, 3. , 5.8, 1.6],
       [7.4, 2.8, 6.1, 1.9],
       [7.9, 3.8, 6.4, 2. ],
       [6.4, 2.8, 5.6, 2.2],
       [6.3, 2.8, 5.1, 1.5],
       [6.1, 2.6, 5.6, 1.4],
       [7.7, 3. , 6.1, 2.3],
       [6.3, 3.4, 5.6, 2.4],
       [6.4, 3.1, 5.5, 1.8],
       [6. , 3. , 4.8, 1.8],
       [6.9, 3.1, 5.4, 2.1],
       [6.7, 3.1, 5.6, 2.4],
       [6.9, 3.1, 5.1, 2.3],
       [5.8, 2.7, 5.1, 1.9],
       [6.8, 3.2, 5.9, 2.3],
       [6.7, 3.3, 5.7, 2.5],
       [6.7, 3. , 5.2, 2.3],
       [6.3, 2.5, 5. , 1.9],
       [6.5, 3. , 5.2, 2. ],
       [6.2, 3.4, 5.4, 2.3],
       [5.9, 3. , 5.1, 1.8]])
data_x=np.insert(data_x,0,1,axis=1)
data_x.shape,data_y.shape
((150, 5), (150, 1))
#训练数据的特征和标签
data_x,data_y
(array([[1. , 5.1, 3.5, 1.4, 0.2],
        [1. , 4.9, 3. , 1.4, 0.2],
        [1. , 4.7, 3.2, 1.3, 0.2],
        [1. , 4.6, 3.1, 1.5, 0.2],
        [1. , 5. , 3.6, 1.4, 0.2],
        [1. , 5.4, 3.9, 1.7, 0.4],
        [1. , 4.6, 3.4, 1.4, 0.3],
        [1. , 5. , 3.4, 1.5, 0.2],
        [1. , 4.4, 2.9, 1.4, 0.2],
        [1. , 4.9, 3.1, 1.5, 0.1],
        [1. , 5.4, 3.7, 1.5, 0.2],
        [1. , 4.8, 3.4, 1.6, 0.2],
        [1. , 4.8, 3. , 1.4, 0.1],
        [1. , 4.3, 3. , 1.1, 0.1],
        [1. , 5.8, 4. , 1.2, 0.2],
        [1. , 5.7, 4.4, 1.5, 0.4],
        [1. , 5.4, 3.9, 1.3, 0.4],
        [1. , 5.1, 3.5, 1.4, 0.3],
        [1. , 5.7, 3.8, 1.7, 0.3],
        [1. , 5.1, 3.8, 1.5, 0.3],
        [1. , 5.4, 3.4, 1.7, 0.2],
        [1. , 5.1, 3.7, 1.5, 0.4],
        [1. , 4.6, 3.6, 1. , 0.2],
        [1. , 5.1, 3.3, 1.7, 0.5],
        [1. , 4.8, 3.4, 1.9, 0.2],
        [1. , 5. , 3. , 1.6, 0.2],
        [1. , 5. , 3.4, 1.6, 0.4],
        [1. , 5.2, 3.5, 1.5, 0.2],
        [1. , 5.2, 3.4, 1.4, 0.2],
        [1. , 4.7, 3.2, 1.6, 0.2],
        [1. , 4.8, 3.1, 1.6, 0.2],
        [1. , 5.4, 3.4, 1.5, 0.4],
        [1. , 5.2, 4.1, 1.5, 0.1],
        [1. , 5.5, 4.2, 1.4, 0.2],
        [1. , 4.9, 3.1, 1.5, 0.2],
        [1. , 5. , 3.2, 1.2, 0.2],
        [1. , 5.5, 3.5, 1.3, 0.2],
        [1. , 4.9, 3.6, 1.4, 0.1],
        [1. , 4.4, 3. , 1.3, 0.2],
        [1. , 5.1, 3.4, 1.5, 0.2],
        [1. , 5. , 3.5, 1.3, 0.3],
        [1. , 4.5, 2.3, 1.3, 0.3],
        [1. , 4.4, 3.2, 1.3, 0.2],
        [1. , 5. , 3.5, 1.6, 0.6],
        [1. , 5.1, 3.8, 1.9, 0.4],
        [1. , 4.8, 3. , 1.4, 0.3],
        [1. , 5.1, 3.8, 1.6, 0.2],
        [1. , 4.6, 3.2, 1.4, 0.2],
        [1. , 5.3, 3.7, 1.5, 0.2],
        [1. , 5. , 3.3, 1.4, 0.2],
        [1. , 7. , 3.2, 4.7, 1.4],
        [1. , 6.4, 3.2, 4.5, 1.5],
        [1. , 6.9, 3.1, 4.9, 1.5],
        [1. , 5.5, 2.3, 4. , 1.3],
        [1. , 6.5, 2.8, 4.6, 1.5],
        [1. , 5.7, 2.8, 4.5, 1.3],
        [1. , 6.3, 3.3, 4.7, 1.6],
        [1. , 4.9, 2.4, 3.3, 1. ],
        [1. , 6.6, 2.9, 4.6, 1.3],
        [1. , 5.2, 2.7, 3.9, 1.4],
        [1. , 5. , 2. , 3.5, 1. ],
        [1. , 5.9, 3. , 4.2, 1.5],
        [1. , 6. , 2.2, 4. , 1. ],
        [1. , 6.1, 2.9, 4.7, 1.4],
        [1. , 5.6, 2.9, 3.6, 1.3],
        [1. , 6.7, 3.1, 4.4, 1.4],
        [1. , 5.6, 3. , 4.5, 1.5],
        [1. , 5.8, 2.7, 4.1, 1. ],
        [1. , 6.2, 2.2, 4.5, 1.5],
        [1. , 5.6, 2.5, 3.9, 1.1],
        [1. , 5.9, 3.2, 4.8, 1.8],
        [1. , 6.1, 2.8, 4. , 1.3],
        [1. , 6.3, 2.5, 4.9, 1.5],
        [1. , 6.1, 2.8, 4.7, 1.2],
        [1. , 6.4, 2.9, 4.3, 1.3],
        [1. , 6.6, 3. , 4.4, 1.4],
        [1. , 6.8, 2.8, 4.8, 1.4],
        [1. , 6.7, 3. , 5. , 1.7],
        [1. , 6. , 2.9, 4.5, 1.5],
        [1. , 5.7, 2.6, 3.5, 1. ],
        [1. , 5.5, 2.4, 3.8, 1.1],
        [1. , 5.5, 2.4, 3.7, 1. ],
        [1. , 5.8, 2.7, 3.9, 1.2],
        [1. , 6. , 2.7, 5.1, 1.6],
        [1. , 5.4, 3. , 4.5, 1.5],
        [1. , 6. , 3.4, 4.5, 1.6],
        [1. , 6.7, 3.1, 4.7, 1.5],
        [1. , 6.3, 2.3, 4.4, 1.3],
        [1. , 5.6, 3. , 4.1, 1.3],
        [1. , 5.5, 2.5, 4. , 1.3],
        [1. , 5.5, 2.6, 4.4, 1.2],
        [1. , 6.1, 3. , 4.6, 1.4],
        [1. , 5.8, 2.6, 4. , 1.2],
        [1. , 5. , 2.3, 3.3, 1. ],
        [1. , 5.6, 2.7, 4.2, 1.3],
        [1. , 5.7, 3. , 4.2, 1.2],
        [1. , 5.7, 2.9, 4.2, 1.3],
        [1. , 6.2, 2.9, 4.3, 1.3],
        [1. , 5.1, 2.5, 3. , 1.1],
        [1. , 5.7, 2.8, 4.1, 1.3],
        [1. , 6.3, 3.3, 6. , 2.5],
        [1. , 5.8, 2.7, 5.1, 1.9],
        [1. , 7.1, 3. , 5.9, 2.1],
        [1. , 6.3, 2.9, 5.6, 1.8],
        [1. , 6.5, 3. , 5.8, 2.2],
        [1. , 7.6, 3. , 6.6, 2.1],
        [1. , 4.9, 2.5, 4.5, 1.7],
        [1. , 7.3, 2.9, 6.3, 1.8],
        [1. , 6.7, 2.5, 5.8, 1.8],
        [1. , 7.2, 3.6, 6.1, 2.5],
        [1. , 6.5, 3.2, 5.1, 2. ],
        [1. , 6.4, 2.7, 5.3, 1.9],
        [1. , 6.8, 3. , 5.5, 2.1],
        [1. , 5.7, 2.5, 5. , 2. ],
        [1. , 5.8, 2.8, 5.1, 2.4],
        [1. , 6.4, 3.2, 5.3, 2.3],
        [1. , 6.5, 3. , 5.5, 1.8],
        [1. , 7.7, 3.8, 6.7, 2.2],
        [1. , 7.7, 2.6, 6.9, 2.3],
        [1. , 6. , 2.2, 5. , 1.5],
        [1. , 6.9, 3.2, 5.7, 2.3],
        [1. , 5.6, 2.8, 4.9, 2. ],
        [1. , 7.7, 2.8, 6.7, 2. ],
        [1. , 6.3, 2.7, 4.9, 1.8],
        [1. , 6.7, 3.3, 5.7, 2.1],
        [1. , 7.2, 3.2, 6. , 1.8],
        [1. , 6.2, 2.8, 4.8, 1.8],
        [1. , 6.1, 3. , 4.9, 1.8],
        [1. , 6.4, 2.8, 5.6, 2.1],
        [1. , 7.2, 3. , 5.8, 1.6],
        [1. , 7.4, 2.8, 6.1, 1.9],
        [1. , 7.9, 3.8, 6.4, 2. ],
        [1. , 6.4, 2.8, 5.6, 2.2],
        [1. , 6.3, 2.8, 5.1, 1.5],
        [1. , 6.1, 2.6, 5.6, 1.4],
        [1. , 7.7, 3. , 6.1, 2.3],
        [1. , 6.3, 3.4, 5.6, 2.4],
        [1. , 6.4, 3.1, 5.5, 1.8],
        [1. , 6. , 3. , 4.8, 1.8],
        [1. , 6.9, 3.1, 5.4, 2.1],
        [1. , 6.7, 3.1, 5.6, 2.4],
        [1. , 6.9, 3.1, 5.1, 2.3],
        [1. , 5.8, 2.7, 5.1, 1.9],
        [1. , 6.8, 3.2, 5.9, 2.3],
        [1. , 6.7, 3.3, 5.7, 2.5],
        [1. , 6.7, 3. , 5.2, 2.3],
        [1. , 6.3, 2.5, 5. , 1.9],
        [1. , 6.5, 3. , 5.2, 2. ],
        [1. , 6.2, 3.4, 5.4, 2.3],
        [1. , 5.9, 3. , 5.1, 1.8]]),
 array([[0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [0],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [1],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2],
        [2]]))

由于有三个类别,那么在训练时三类数据要分开

data1=data.copy()
data1
ones F1 F2 F3 F4 target
0 1 5.1 3.5 1.4 0.2 0
1 1 4.9 3.0 1.4 0.2 0
2 1 4.7 3.2 1.3 0.2 0
3 1 4.6 3.1 1.5 0.2 0
4 1 5.0 3.6 1.4 0.2 0
... ... ... ... ... ... ...
145 1 6.7 3.0 5.2 2.3 2
146 1 6.3 2.5 5.0 1.9 2
147 1 6.5 3.0 5.2 2.0 2
148 1 6.2 3.4 5.4 2.3 2
149 1 5.9 3.0 5.1 1.8 2

150 rows × 6 columns

data

data1.loc[data["target"]!=0,"target"]=0
data1.loc[data["target"]==0,"target"]=1
data1
ones F1 F2 F3 F4 target
0 1 5.1 3.5 1.4 0.2 1
1 1 4.9 3.0 1.4 0.2 1
2 1 4.7 3.2 1.3 0.2 1
3 1 4.6 3.1 1.5 0.2 1
4 1 5.0 3.6 1.4 0.2 1
... ... ... ... ... ... ...
145 1 6.7 3.0 5.2 2.3 0
146 1 6.3 2.5 5.0 1.9 0
147 1 6.5 3.0 5.2 2.0 0
148 1 6.2 3.4 5.4 2.3 0
149 1 5.9 3.0 5.1 1.8 0

150 rows × 6 columns

data1_x=data1.iloc[:,:data1.shape[1]-1].values
data1_y=data1.iloc[:,data1.shape[1]-1].values
data1_x.shape,data1_y.shape
((150, 5), (150,))
#针对第二类,即第二个分类器的数据
data2=data.copy()
data2.loc[data["target"]==1,"target"]=1
data2.loc[data["target"]!=1,"target"]=0
data2["target"]==0
0      True
1      True
2      True
3      True
4      True
       ... 
145    True
146    True
147    True
148    True
149    True
Name: target, Length: 150, dtype: bool
data2.shape[1]
6
data2.iloc[50:55,:]
ones F1 F2 F3 F4 target
50 1 7.0 3.2 4.7 1.4 1
51 1 6.4 3.2 4.5 1.5 1
52 1 6.9 3.1 4.9 1.5 1
53 1 5.5 2.3 4.0 1.3 1
54 1 6.5 2.8 4.6 1.5 1
data2_x=data2.iloc[:,:data2.shape[1]-1].values
data2_y=data2.iloc[:,data2.shape[1]-1].values
#针对第三类,即第三个分类器的数据
data3=data.copy()
data3.loc[data["target"]==2,"target"]=1
data3.loc[data["target"]!=2,"target"]=0
data3
ones F1 F2 F3 F4 target
0 1 5.1 3.5 1.4 0.2 0
1 1 4.9 3.0 1.4 0.2 0
2 1 4.7 3.2 1.3 0.2 0
3 1 4.6 3.1 1.5 0.2 0
4 1 5.0 3.6 1.4 0.2 0
... ... ... ... ... ... ...
145 1 6.7 3.0 5.2 2.3 1
146 1 6.3 2.5 5.0 1.9 1
147 1 6.5 3.0 5.2 2.0 1
148 1 6.2 3.4 5.4 2.3 1
149 1 5.9 3.0 5.1 1.8 1

150 rows × 6 columns

data3_x=data3.iloc[:,:data3.shape[1]-1].values
data3_y=data3.iloc[:,data3.shape[1]-1].values

1.3 定义假设函数,代价函数,梯度下降算法(从实验3复制过来)

def sigmoid(z):
    return 1 / (1 + np.exp(-z))
def h(X,w):
    z=X@w
    h=sigmoid(z)
    return h
#代价函数构造
def cost(X,w,y):
    #当X(m,n+1),y(m,),w(n+1,1)
    y_hat=sigmoid(X@w)
    right=np.multiply(y.ravel(),np.log(y_hat).ravel())+np.multiply((1-y).ravel(),np.log(1-y_hat).ravel())
    cost=-np.sum(right)/X.shape[0]
    return cost
def sigmoid(z):
    return 1 / (1 + np.exp(-z))

def h(X,w):
    z=X@w
    h=sigmoid(z)
    return h

#代价函数构造
def cost(X,w,y):
    #当X(m,n+1),y(m,),w(n+1,1)
    y_hat=sigmoid(X@w)
    right=np.multiply(y.ravel(),np.log(y_hat).ravel())+np.multiply((1-y).ravel(),np.log(1-y_hat).ravel())
    cost=-np.sum(right)/X.shape[0]
    return cost



def grandient(X,y,iter_num,alpha):
    y=y.reshape((X.shape[0],1))
    w=np.zeros((X.shape[1],1))
    cost_lst=[]  
    for i in range(iter_num):
        y_pred=h(X,w)-y
        temp=np.zeros((X.shape[1],1))
        for j in range(X.shape[1]):
            right=np.multiply(y_pred.ravel(),X[:,j])
            
            gradient=1/(X.shape[0])*(np.sum(right))
            temp[j,0]=w[j,0]-alpha*gradient
        w=temp
        cost_lst.append(cost(X,w,y.ravel()))
    return w,cost_lst

1.4 调用梯度下降算法来学习三个分类模型的参数

#初始化超参数
iter_num,alpha=600000,0.001
#训练第一个模型
w1,cost_lst1=grandient(data1_x,data1_y,iter_num,alpha)
import matplotlib.pyplot as plt
plt.plot(range(iter_num),cost_lst1,"b-o")
[]

【Python机器学习】实验04(1) 多分类(基于逻辑回归)实践_第1张图片

#训练第二个模型
w2,cost_lst2=grandient(data2_x,data2_y,iter_num,alpha)
import matplotlib.pyplot as plt
plt.plot(range(iter_num),cost_lst2,"b-o")
[]

【Python机器学习】实验04(1) 多分类(基于逻辑回归)实践_第2张图片

#训练第三个模型
w3,cost_lst3=grandient(data3_x,data3_y,iter_num,alpha)
w3
array([[-3.22437049],
       [-3.50214058],
       [-3.50286355],
       [ 5.16580317],
       [ 5.89898368]])
import matplotlib.pyplot as plt
plt.plot(range(iter_num),cost_lst3,"b-o")
[]

【Python机器学习】实验04(1) 多分类(基于逻辑回归)实践_第3张图片

1.5 利用模型进行预测

h(data_x,w3)
array([[1.48445441e-11],
       [1.72343968e-10],
       [1.02798153e-10],
       [5.81975546e-10],
       [1.48434710e-11],
       [1.95971176e-11],
       [2.18959639e-10],
       [5.01346874e-11],
       [1.40930075e-09],
       [1.12830635e-10],
       [4.31888744e-12],
       [1.69308343e-10],
       [1.35613372e-10],
       [1.65858883e-10],
       [7.89880725e-14],
       [4.23224675e-13],
       [2.48199140e-12],
       [2.67766642e-11],
       [5.39314286e-12],
       [1.56935848e-11],
       [3.47096426e-11],
       [4.01827075e-11],
       [7.63005509e-12],
       [8.26864773e-10],
       [7.97484594e-10],
       [3.41189783e-10],
       [2.73442178e-10],
       [1.75314894e-11],
       [1.48456174e-11],
       [4.84204982e-10],
       [4.84239990e-10],
       [4.01914238e-11],
       [1.18813180e-12],
       [3.14985611e-13],
       [2.03524473e-10],
       [2.14461446e-11],
       [2.18189955e-12],
       [1.16799745e-11],
       [5.92281641e-10],
       [3.53217554e-11],
       [2.26727669e-11],
       [8.74004884e-09],
       [2.93949962e-10],
       [6.26783110e-10],
       [2.23513465e-10],
       [4.41246960e-10],
       [1.45841303e-11],
       [2.44584721e-10],
       [6.13010507e-12],
       [4.24539165e-11],
       [1.64123143e-03],
       [8.55503211e-03],
       [1.65105645e-02],
       [9.87814122e-02],
       [3.97290777e-02],
       [1.11076040e-01],
       [4.19003715e-02],
       [2.88426221e-03],
       [6.27161978e-03],
       [7.67020481e-02],
       [2.27204861e-02],
       [2.08212169e-02],
       [4.58067633e-03],
       [9.90450665e-02],
       [1.19419048e-03],
       [1.41462060e-03],
       [2.22638069e-01],
       [2.68940904e-03],
       [3.66014737e-01],
       [6.97791873e-03],
       [5.78803255e-01],
       [2.32071970e-03],
       [5.28941621e-01],
       [4.57649874e-02],
       [2.69208900e-03],
       [2.84603646e-03],
       [2.20421076e-02],
       [2.07507605e-01],
       [9.10460936e-02],
       [2.44824946e-04],
       [8.37509821e-03],
       [2.78543808e-03],
       [3.11283202e-03],
       [8.89831833e-01],
       [3.65880536e-01],
       [3.03993844e-02],
       [1.18930239e-02],
       [4.99150151e-02],
       [1.10252946e-02],
       [5.15923462e-02],
       [1.43653056e-01],
       [4.41610209e-02],
       [7.37513950e-03],
       [2.88447014e-03],
       [5.07366744e-02],
       [7.24617687e-03],
       [1.83460602e-02],
       [5.40874928e-03],
       [3.87210511e-04],
       [1.55791816e-02],
       [9.99862942e-01],
       [9.89637526e-01],
       [9.86183040e-01],
       [9.83705644e-01],
       [9.98410187e-01],
       [9.97834502e-01],
       [9.84208537e-01],
       [9.85434538e-01],
       [9.94141336e-01],
       [9.94561329e-01],
       [7.20333384e-01],
       [9.70431293e-01],
       [9.62754456e-01],
       [9.96609064e-01],
       [9.99222270e-01],
       [9.83684437e-01],
       [9.26437633e-01],
       [9.83486260e-01],
       [9.99950496e-01],
       [9.39002061e-01],
       [9.88043323e-01],
       [9.88637702e-01],
       [9.98357641e-01],
       [7.65848930e-01],
       [9.73006160e-01],
       [8.76969899e-01],
       [6.61137141e-01],
       [6.97324053e-01],
       [9.97185846e-01],
       [6.11033594e-01],
       [9.77494647e-01],
       [6.58573810e-01],
       [9.98437920e-01],
       [5.24529693e-01],
       [9.70465066e-01],
       [9.87624920e-01],
       [9.97236435e-01],
       [9.26432706e-01],
       [6.61104746e-01],
       [8.84442100e-01],
       [9.96082862e-01],
       [8.40940308e-01],
       [9.89637526e-01],
       [9.96974990e-01],
       [9.97386310e-01],
       [9.62040470e-01],
       [9.52214579e-01],
       [8.96902215e-01],
       [9.90200940e-01],
       [9.28785160e-01]])
#将数据输入三个模型的看看结果
multi_pred=pd.DataFrame(zip(h(data_x,w1).ravel(),h(data_x,w2).ravel(),h(data_x,w3).ravel()))
multi_pred
0 1 2
0 0.999297 0.108037 1.484454e-11
1 0.997061 0.270814 1.723440e-10
2 0.998633 0.164710 1.027982e-10
3 0.995774 0.231910 5.819755e-10
4 0.999415 0.085259 1.484347e-11
... ... ... ...
145 0.000007 0.127574 9.620405e-01
146 0.000006 0.496389 9.522146e-01
147 0.000010 0.234745 8.969022e-01
148 0.000006 0.058444 9.902009e-01
149 0.000014 0.284295 9.287852e-01

150 rows × 3 columns

multi_pred.values[:3]
array([[9.99297209e-01, 1.08037473e-01, 1.48445441e-11],
       [9.97060801e-01, 2.70813780e-01, 1.72343968e-10],
       [9.98632728e-01, 1.64709623e-01, 1.02798153e-10]])
#每个样本的预测值
np.argmax(multi_pred.values,axis=1)
array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
       1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1,
       1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
       2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2,
       2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2], dtype=int64)
#每个样本的真实值
data_y
array([[0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [0],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [1],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2],
       [2]])

1.6 评估模型

np.argmax(multi_pred.values,axis=1)==data_y.ravel()
array([ True,  True,  True,  True,  True,  True,  True,  True,  True,
        True,  True,  True,  True,  True,  True,  True,  True,  True,
        True,  True,  True,  True,  True,  True,  True,  True,  True,
        True,  True,  True,  True,  True,  True,  True,  True,  True,
        True,  True,  True,  True,  True,  True,  True,  True,  True,
        True,  True,  True,  True,  True,  True,  True,  True,  True,
        True,  True,  True,  True,  True,  True,  True,  True,  True,
        True,  True,  True,  True,  True,  True,  True, False,  True,
        True,  True,  True,  True,  True,  True,  True,  True,  True,
        True,  True, False, False,  True,  True,  True,  True,  True,
        True,  True,  True,  True,  True,  True,  True,  True,  True,
        True,  True,  True,  True,  True,  True,  True,  True,  True,
        True,  True,  True,  True,  True,  True,  True,  True,  True,
        True,  True,  True,  True,  True,  True,  True,  True,  True,
        True,  True,  True, False,  True,  True,  True, False,  True,
        True,  True,  True,  True,  True,  True,  True,  True,  True,
        True,  True,  True,  True,  True,  True])
np.sum(np.argmax(multi_pred.values,axis=1)==data_y.ravel())
145
np.sum(np.argmax(multi_pred.values,axis=1)==data_y.ravel())/len(data)
0.9666666666666667

1.7 试试sklearn

from sklearn.linear_model import LogisticRegression
#建立第一个模型
clf1=LogisticRegression()
clf1.fit(data1_x,data1_y)
#建立第二个模型
clf2=LogisticRegression()
clf2.fit(data2_x,data2_y)
#建立第三个模型
clf3=LogisticRegression()
clf3.fit(data3_x,data3_y)
LogisticRegression()
y_pred1=clf1.predict(data_x)
y_pred2=clf2.predict(data_x)
y_pred3=clf3.predict(data_x)
#可视化各模型的预测结果
multi_pred=pd.DataFrame(zip(y_pred1,y_pred2,y_pred3),columns=["模型1","模糊2","模型3"])
multi_pred
模型1 模糊2 模型3
0 1 0 0
1 1 0 0
2 1 0 0
3 1 0 0
4 1 0 0
... ... ... ...
145 0 0 1
146 0 1 1
147 0 0 1
148 0 0 1
149 0 0 1

150 rows × 3 columns

#判断预测结果
np.argmax(multi_pred.values,axis=1)
array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0,
       0, 1, 1, 1, 2, 0, 1, 1, 0, 0, 0, 2, 0, 1, 1, 1, 0, 1, 0, 0, 0, 1,
       0, 1, 1, 0, 1, 1, 1, 0, 0, 0, 1, 0, 2, 2, 2, 2, 2, 2, 1, 1, 1, 2,
       2, 2, 2, 1, 2, 2, 2, 2, 1, 1, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 1, 2,
       2, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2], dtype=int64)
data_y.ravel()
array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
       1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
       1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
       2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
       2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2])
#计算准确率
np.sum(np.argmax(multi_pred.values,axis=1)==data_y.ravel())/data.shape[0]
0.7333333333333333

实验4(1) 请动手完成你们第一个多分类问题,祝好运!完成下面代码

2.1 数据读取

data_x,data_y=datasets.make_blobs(n_samples=200, n_features=6,  centers=4,random_state=0)
data_x.shape,data_y.shape
((200, 6), (200,))

2.2 训练数据的准备

data=np.insert(data_x,data_x.shape[1],data_y,axis=1)
data=pd.DataFrame(data,columns=["F1","F2","F3","F4","F5","F6","target"])
data
F1 F2 F3 F4 F5 F6 target
0 2.116632 7.972800 -9.328969 -8.224605 -12.178429 5.498447 2.0
1 1.886449 4.621006 2.841595 0.431245 -2.471350 2.507833 0.0
2 2.391329 6.464609 -9.805900 -7.289968 -9.650985 6.388460 2.0
3 -1.034776 6.626886 9.031235 -0.812908 5.449855 0.134062 1.0
4 -0.481593 8.191753 7.504717 -1.975688 6.649021 0.636824 1.0
... ... ... ... ... ... ... ...
195 5.434893 7.128471 9.789546 6.061382 0.634133 5.757024 3.0
196 -0.406625 7.586001 9.322750 -1.837333 6.477815 -0.992725 1.0
197 2.031462 7.804427 -8.539512 -9.824409 -10.046935 6.918085 2.0
198 4.081889 6.127685 11.091126 4.812011 -0.005915 5.342211 3.0
199 0.985744 7.285737 -8.395940 -6.586471 -9.651765 6.651012 2.0

200 rows × 7 columns

data["target"]=data["target"].astype("int32")
data
F1 F2 F3 F4 F5 F6 target
0 2.116632 7.972800 -9.328969 -8.224605 -12.178429 5.498447 2
1 1.886449 4.621006 2.841595 0.431245 -2.471350 2.507833 0
2 2.391329 6.464609 -9.805900 -7.289968 -9.650985 6.388460 2
3 -1.034776 6.626886 9.031235 -0.812908 5.449855 0.134062 1
4 -0.481593 8.191753 7.504717 -1.975688 6.649021 0.636824 1
... ... ... ... ... ... ... ...
195 5.434893 7.128471 9.789546 6.061382 0.634133 5.757024 3
196 -0.406625 7.586001 9.322750 -1.837333 6.477815 -0.992725 1
197 2.031462 7.804427 -8.539512 -9.824409 -10.046935 6.918085 2
198 4.081889 6.127685 11.091126 4.812011 -0.005915 5.342211 3
199 0.985744 7.285737 -8.395940 -6.586471 -9.651765 6.651012 2

200 rows × 7 columns

data.insert(0,"ones",1)
data
ones F1 F2 F3 F4 F5 F6 target
0 1 2.116632 7.972800 -9.328969 -8.224605 -12.178429 5.498447 2
1 1 1.886449 4.621006 2.841595 0.431245 -2.471350 2.507833 0
2 1 2.391329 6.464609 -9.805900 -7.289968 -9.650985 6.388460 2
3 1 -1.034776 6.626886 9.031235 -0.812908 5.449855 0.134062 1
4 1 -0.481593 8.191753 7.504717 -1.975688 6.649021 0.636824 1
... ... ... ... ... ... ... ... ...
195 1 5.434893 7.128471 9.789546 6.061382 0.634133 5.757024 3
196 1 -0.406625 7.586001 9.322750 -1.837333 6.477815 -0.992725 1
197 1 2.031462 7.804427 -8.539512 -9.824409 -10.046935 6.918085 2
198 1 4.081889 6.127685 11.091126 4.812011 -0.005915 5.342211 3
199 1 0.985744 7.285737 -8.395940 -6.586471 -9.651765 6.651012 2

200 rows × 8 columns

#第一个类别的数据
data1=data.copy()
data1.loc[data["target"]==0,"target"]=1
data1.loc[data["target"]!=0,"target"]=0
data1
ones F1 F2 F3 F4 F5 F6 target
0 1 2.116632 7.972800 -9.328969 -8.224605 -12.178429 5.498447 0
1 1 1.886449 4.621006 2.841595 0.431245 -2.471350 2.507833 1
2 1 2.391329 6.464609 -9.805900 -7.289968 -9.650985 6.388460 0
3 1 -1.034776 6.626886 9.031235 -0.812908 5.449855 0.134062 0
4 1 -0.481593 8.191753 7.504717 -1.975688 6.649021 0.636824 0
... ... ... ... ... ... ... ... ...
195 1 5.434893 7.128471 9.789546 6.061382 0.634133 5.757024 0
196 1 -0.406625 7.586001 9.322750 -1.837333 6.477815 -0.992725 0
197 1 2.031462 7.804427 -8.539512 -9.824409 -10.046935 6.918085 0
198 1 4.081889 6.127685 11.091126 4.812011 -0.005915 5.342211 0
199 1 0.985744 7.285737 -8.395940 -6.586471 -9.651765 6.651012 0

200 rows × 8 columns

data1_x=data1.iloc[:,:data1.shape[1]-1].values
data1_y=data1.iloc[:,data1.shape[1]-1].values
data1_x.shape,data1_y.shape
((200, 7), (200,))
#第二个类别的数据
data2=data.copy()
data2.loc[data["target"]==1,"target"]=1
data2.loc[data["target"]!=1,"target"]=0
data2
ones F1 F2 F3 F4 F5 F6 target
0 1 2.116632 7.972800 -9.328969 -8.224605 -12.178429 5.498447 0
1 1 1.886449 4.621006 2.841595 0.431245 -2.471350 2.507833 0
2 1 2.391329 6.464609 -9.805900 -7.289968 -9.650985 6.388460 0
3 1 -1.034776 6.626886 9.031235 -0.812908 5.449855 0.134062 1
4 1 -0.481593 8.191753 7.504717 -1.975688 6.649021 0.636824 1
... ... ... ... ... ... ... ... ...
195 1 5.434893 7.128471 9.789546 6.061382 0.634133 5.757024 0
196 1 -0.406625 7.586001 9.322750 -1.837333 6.477815 -0.992725 1
197 1 2.031462 7.804427 -8.539512 -9.824409 -10.046935 6.918085 0
198 1 4.081889 6.127685 11.091126 4.812011 -0.005915 5.342211 0
199 1 0.985744 7.285737 -8.395940 -6.586471 -9.651765 6.651012 0

200 rows × 8 columns

data2_x=data2.iloc[:,:data2.shape[1]-1].values
data2_y=data2.iloc[:,data2.shape[1]-1].values
#第三个类别的数据
data3=data.copy()
data3.loc[data["target"]==2,"target"]=1
data3.loc[data["target"]!=2,"target"]=0
data3
ones F1 F2 F3 F4 F5 F6 target
0 1 2.116632 7.972800 -9.328969 -8.224605 -12.178429 5.498447 1
1 1 1.886449 4.621006 2.841595 0.431245 -2.471350 2.507833 0
2 1 2.391329 6.464609 -9.805900 -7.289968 -9.650985 6.388460 1
3 1 -1.034776 6.626886 9.031235 -0.812908 5.449855 0.134062 0
4 1 -0.481593 8.191753 7.504717 -1.975688 6.649021 0.636824 0
... ... ... ... ... ... ... ... ...
195 1 5.434893 7.128471 9.789546 6.061382 0.634133 5.757024 0
196 1 -0.406625 7.586001 9.322750 -1.837333 6.477815 -0.992725 0
197 1 2.031462 7.804427 -8.539512 -9.824409 -10.046935 6.918085 1
198 1 4.081889 6.127685 11.091126 4.812011 -0.005915 5.342211 0
199 1 0.985744 7.285737 -8.395940 -6.586471 -9.651765 6.651012 1

200 rows × 8 columns

data3_x=data3.iloc[:,:data3.shape[1]-1].values
data3_y=data3.iloc[:,data3.shape[1]-1].values
#第四个类别的数据
data4=data.copy()
data4.loc[data["target"]==3,"target"]=1
data4.loc[data["target"]!=3,"target"]=0
data4
ones F1 F2 F3 F4 F5 F6 target
0 1 2.116632 7.972800 -9.328969 -8.224605 -12.178429 5.498447 0
1 1 1.886449 4.621006 2.841595 0.431245 -2.471350 2.507833 0
2 1 2.391329 6.464609 -9.805900 -7.289968 -9.650985 6.388460 0
3 1 -1.034776 6.626886 9.031235 -0.812908 5.449855 0.134062 0
4 1 -0.481593 8.191753 7.504717 -1.975688 6.649021 0.636824 0
... ... ... ... ... ... ... ... ...
195 1 5.434893 7.128471 9.789546 6.061382 0.634133 5.757024 1
196 1 -0.406625 7.586001 9.322750 -1.837333 6.477815 -0.992725 0
197 1 2.031462 7.804427 -8.539512 -9.824409 -10.046935 6.918085 0
198 1 4.081889 6.127685 11.091126 4.812011 -0.005915 5.342211 1
199 1 0.985744 7.285737 -8.395940 -6.586471 -9.651765 6.651012 0

200 rows × 8 columns

data4_x=data4.iloc[:,:data4.shape[1]-1].values
data4_y=data4.iloc[:,data4.shape[1]-1].values

2.3 定义假设函数、代价函数和梯度下降算法

def sigmoid(z):
    return 1 / (1 + np.exp(-z))
def h(X,w):
    z=X@w
    h=sigmoid(z)
    return h
#代价函数构造
def cost(X,w,y):
    #当X(m,n+1),y(m,),w(n+1,1)
    y_hat=sigmoid(X@w)
    right=np.multiply(y.ravel(),np.log(y_hat).ravel())+np.multiply((1-y).ravel(),np.log(1-y_hat).ravel())
    cost=-np.sum(right)/X.shape[0]
    return cost
def grandient(X,y,iter_num,alpha):
    y=y.reshape((X.shape[0],1))
    w=np.zeros((X.shape[1],1))
    cost_lst=[]  
    for i in range(iter_num):
        y_pred=h(X,w)-y
        temp=np.zeros((X.shape[1],1))
        for j in range(X.shape[1]):
            right=np.multiply(y_pred.ravel(),X[:,j])
            
            gradient=1/(X.shape[0])*(np.sum(right))
            temp[j,0]=w[j,0]-alpha*gradient
        w=temp
        cost_lst.append(cost(X,w,y.ravel()))
    return w,cost_lst

2.4 学习这四个分类模型

import matplotlib.pyplot as plt
#初始化超参数
iter_num,alpha=600000,0.001
#训练第1个模型
w1,cost_lst1=grandient(data1_x,data1_y,iter_num,alpha)
plt.plot(range(iter_num),cost_lst1,"b-o")
[]

【Python机器学习】实验04(1) 多分类(基于逻辑回归)实践_第4张图片

#训练第2个模型
w2,cost_lst2=grandient(data2_x,data2_y,iter_num,alpha)
plt.plot(range(iter_num),cost_lst2,"b-o")
[]

【Python机器学习】实验04(1) 多分类(基于逻辑回归)实践_第5张图片

#训练第3个模型
w3,cost_lst3=grandient(data3_x,data3_y,iter_num,alpha)
plt.plot(range(iter_num),cost_lst3,"b-o")
[]

【Python机器学习】实验04(1) 多分类(基于逻辑回归)实践_第6张图片

#训练第4个模型
w4,cost_lst4=grandient(data4_x,data4_y,iter_num,alpha)
plt.plot(range(iter_num),cost_lst4,"b-o")
[]

【Python机器学习】实验04(1) 多分类(基于逻辑回归)实践_第7张图片

2.5 利用模型进行预测

data_x
array([[ 2.11663151e+00,  7.97280013e+00, -9.32896918e+00,
        -8.22460526e+00, -1.21784287e+01,  5.49844655e+00],
       [ 1.88644899e+00,  4.62100554e+00,  2.84159548e+00,
         4.31244563e-01, -2.47135027e+00,  2.50783257e+00],
       [ 2.39132949e+00,  6.46460915e+00, -9.80590050e+00,
        -7.28996786e+00, -9.65098460e+00,  6.38845956e+00],
       ...,
       [ 2.03146167e+00,  7.80442707e+00, -8.53951210e+00,
        -9.82440872e+00, -1.00469351e+01,  6.91808489e+00],
       [ 4.08188906e+00,  6.12768483e+00,  1.10911262e+01,
         4.81201082e+00, -5.91530191e-03,  5.34221079e+00],
       [ 9.85744105e-01,  7.28573657e+00, -8.39593964e+00,
        -6.58647097e+00, -9.65176507e+00,  6.65101187e+00]])
data_x=np.insert(data_x,0,1,axis=1)
data_x.shape
(200, 7)
w3.shape
(7, 1)
multi_pred=pd.DataFrame(zip(h(data_x,w1).ravel(),h(data_x,w2).ravel(),h(data_x,w3).ravel(),h(data_x,w4).ravel()))
multi_pred
0 1 2 3
0 0.020436 4.556248e-15 9.999975e-01 2.601227e-27
1 0.820488 4.180906e-05 3.551499e-05 5.908691e-05
2 0.109309 7.316201e-14 9.999978e-01 7.091713e-24
3 0.036608 9.999562e-01 1.048562e-09 5.724854e-03
4 0.003075 9.999292e-01 2.516742e-09 6.423038e-05
... ... ... ... ...
195 0.017278 3.221293e-06 3.753372e-14 9.999943e-01
196 0.003369 9.999966e-01 6.673394e-10 2.281428e-03
197 0.000606 1.118174e-13 9.999941e-01 1.780212e-28
198 0.013072 4.999118e-05 9.811154e-14 9.996689e-01
199 0.151548 1.329623e-13 9.999447e-01 2.571989e-24

200 rows × 4 columns

2.6 计算准确率

np.sum(np.argmax(multi_pred.values,axis=1)==data_y.ravel())/len(data)
1.0

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