使用sklean进行多分类下的二分类

Posted 2020-10-16 similarface

#coding:utf-8
import matplotlib.pyplot as plt
import numpy as np
from sklearn.linear_model import LogisticRegression
from sklearn.svm import SVC
from sklearn.gaussian_process import GaussianProcessClassifier
from sklearn.gaussian_process.kernels import RBF
from sklearn import datasets

iris = datasets.load_iris()

#花萼长度    花萼宽度
X = iris.data[:, 0:2]  # we only take the first two features for visualization
#所属种类
y = iris.target

print X.shape
print y
#两个因数
n_features = X.shape[1]

C = 1.0
kernel = 1.0 * RBF([1.0, 1.0])  # for GPC

# Create different classifiers. The logistic regression cannot do
# multiclass out of the box.
classifiers = {\'L1 logistic\': LogisticRegression(C=C, penalty=\'l1\'),
               \'L2 logistic (OvR)\': LogisticRegression(C=C, penalty=\'l2\'),
               \'Linear SVC\': SVC(kernel=\'linear\', C=C, probability=True,random_state=0),
               \'L2 logistic (Multinomial)\': LogisticRegression(C=C, solver=\'lbfgs\', multi_class=\'multinomial\'),
               \'GPC\': GaussianProcessClassifier(kernel)
               }

n_classifiers = len(classifiers)

plt.figure(figsize=(3 * 2, n_classifiers * 2))
plt.subplots_adjust(bottom=.2, top=.95)

#3-9 的100个平均分布的值
xx = np.linspace(3, 9, 100)
#1-5 的100个平均分布的值
yy = np.linspace(1, 5, 100).T

#
xx, yy = np.meshgrid(xx, yy)

#纵列连接数据 构造虚拟：花萼长度    花萼宽度
Xfull = np.c_[xx.ravel(), yy.ravel()]

for index, (name, classifier) in enumerate(classifiers.items()):
    classifier.fit(X, y)

    y_pred = classifier.predict(X)
    classif_rate = np.mean(y_pred.ravel() == y.ravel()) * 100
    print("classif_rate for %s : %f " % (name, classif_rate))

    # 查看预测概率
    probas = classifier.predict_proba(Xfull)
    #3个种类
    n_classes = np.unique(y_pred).size
    for k in range(n_classes):
        plt.subplot(n_classifiers, n_classes, index * n_classes + k + 1)
        plt.title("Class %d" % k)
        if k == 0:
            plt.ylabel(name)
        #构造颜色
        imshow_handle = plt.imshow(probas[:, k].reshape((100, 100)),extent=(3, 9, 1, 5), origin=\'lower\')
        plt.xticks(())
        plt.yticks(())
        idx = (y_pred == k)
        if idx.any():
            plt.scatter(X[idx, 0], X[idx, 1], marker=\'o\', c=\'k\')

ax = plt.axes([0.15, 0.04, 0.7, 0.05])
plt.title("Probability")
plt.colorbar(imshow_handle, cax=ax, orientation=\'horizontal\')

plt.show()