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方差（variance）

方差用来描述数据和均值之间的偏离程度 。${\sigma }^2=$ 读作 sigma square

方差公式：${\sigma }^2=\frac{{\sum }_{i=1}^N(x_i-\mu {)}^2}{N}$

Python

import numpy as np# 定义数据集data_set1 = np.array([2, 2, 3, 3])data_set2 = np.array([0, 0, 5, 5])print(f'data_set1={data_set1}')print(f'data_set2={data_set2}')# 均值mean1 = np.mean(data_set1)mean2 = np.mean(data_set2)print(f'mean of data_set1 = {mean1}')print(f'mean of data_set2 = {mean2}')# 方差variance1 = np.var(data_set1)variance2 = np.var(data_set2)print(f'variance of data_set1 = {variance1}')print(f'variance of data_set2 = {variance2}')

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