给出python实现高斯贝叶斯分类的代码,处理鸢尾花数据集,不调用sklearn库,实现结果可视化
时间: 2023-06-03 18:01:49 浏览: 164
决策树对鸢尾花数据两特征组合分类python代码的结果-决策树可视化
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下面是 Python 实现高斯朴素贝叶斯分类算法的代码,用于处理鸢尾花数据集,并可以实现结果的可视化:
```python
import numpy as np
import matplotlib.pyplot as plt
from scipy.stats import norm
# 加载鸢尾花数据集
iris_data = np.loadtxt('iris.data', delimiter=',', usecols=[0, 1, 2, 3])
iris_labels = np.loadtxt('iris.data', delimiter=',', usecols=[4], dtype='str')
# 数据集划分为训练集和测试集
train_data = np.concatenate([iris_data[0:40, :], iris_data[50:90, :], iris_data[100:140, :]])
train_labels = np.concatenate([iris_labels[0:40], iris_labels[50:90], iris_labels[100:140]])
test_data = np.concatenate([iris_data[40:50, :], iris_data[90:100, :], iris_data[140:150, :]])
test_labels = np.concatenate([iris_labels[40:50], iris_labels[90:100], iris_labels[140:150]])
# 按照类别分割训练数据
train_data_by_class = [train_data[train_labels == label] for label in np.unique(train_labels)]
train_labels_by_class = [train_labels[train_labels == label] for label in np.unique(train_labels)]
# 计算每个类别的先验概率
class_prior_probs = [len(label) / float(len(train_labels)) for label in train_labels_by_class]
# 计算每个类别中每个特征的均值和方差
class_mean_var = []
for class_data in train_data_by_class:
class_mean_var.append([(np.mean(feature), np.var(feature)) for feature in class_data.T])
# 定义高斯分布函数
def gaussian(x, mean, var):
return norm.pdf(x, mean, np.sqrt(var))
# 通过计算后验概率,预测测试数据的分类
def predict_class(test_data):
posteriors = []
for i in range(len(np.unique(train_labels))):
class_posterior = class_prior_probs[i]
for feature, class_mean_var_ in zip(test_data, class_mean_var[i]):
class_posterior *= gaussian(feature, class_mean_var_[0], class_mean_var_[1])
posteriors.append(class_posterior)
return np.argmax(posteriors)
# 对测试数据进行分类并保存结果
predicted_labels = []
for test_sample in test_data:
predicted_labels.append(predict_class(test_sample))
# 计算分类准确率
accuracy = np.mean(predicted_labels == test_labels)
print('Classification accuracy:', accuracy)
# 可视化分类结果
colors = {'Iris-setosa': 'r', 'Iris-versicolor': 'g', 'Iris-virginica': 'b'}
markers = {'Iris-setosa': 'o', 'Iris-versicolor': 's', 'Iris-virginica': '^'}
for i in range(len(test_labels)):
plt.scatter(test_data[i, 0], test_data[i, 1], color=colors[test_labels[i]],
marker=markers[test_labels[i]])
plt.scatter(test_data[i, 0], test_data[i, 1], color=colors[predicted_labels[i]],
marker='x')
plt.xlabel('Sepal length')
plt.ylabel('Sepal width')
plt.show()
```
以上就是用于实现高斯朴素贝叶斯分类器的代码,带有鸢尾花数据集的处理及分类结果的可视化。
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