11.25

逻辑回归（对数几率回归）是一种分类算法，通过 Sigmoid 函数将线性回归的输出（连续值）映射到 [0,1] 区间，用于表示类别概率。对于多分类问题（如 Iris 数据集的 3 类花），采用one-vs-rest（默认）或multinomial策略实现。
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
from sklearn.datasets import load_iris
from sklearn.preprocessing import StandardScaler
from sklearn.linear_model import LogisticRegression
from sklearn.model_selection import cross_validate, StratifiedKFold
from sklearn.metrics import accuracy_score, precision_score, recall_score, f1_score
import warnings
warnings.filterwarnings('ignore') # 忽略警告

设置中文显示

plt.rcParams['font.sans-serif'] = ['SimHei']
plt.rcParams['axes.unicode_minus'] = False