#加载numpy包 import numpy #加载sklearn包 from sklearn.datasets import load_iris data=load_iris() #鸢尾花花瓣长度的数据 petal_length=numpy.array(list(len[2] for len in data['data'])) print(petal_length)
#计算鸢尾花花瓣长度的最大值,平均值,中值,均方差 print(numpy.max(petal_length)) print(numpy.mean(petal_length)) print(numpy.median(petal_length)) print(numpy.std(petal_length))
#用np.random.normal()产生一个正态分布的随机数组,并显示出来 import numpy as np import matplotlib.pyplot as plt mu = 5 #期望为5 sigma = 3 #标准差为3 num = 1000 #个数为1000 normal_data = np.random.normal(mu, sigma, num) print(normal_data) #用np.random.randn()产生一个正态分布的随机数组,并显示出来 a=np.random.random(25) print(a)
#显示鸢尾花花瓣长度的正态分布图,曲线图,散点图 import numpy as np import matplotlib.pyplot as plt mu=np.mean(petal_length) sigma =np.std(petal_length) num=1000 normal_data = np.random.normal(mu, sigma, num) count, bins, ignored = plt.hist(normal_data, 30, normed=True) plt.plot(bins, 1/(sigma * np.sqrt(2 * np.pi)) *np.exp( - (bins - mu)**2 / (2 * sigma**2)), linewidth=2, color='orange') plt.show() plt.plot(numpy.linspace(0,150,num=150),petal_length,color='orange') plt.show() plt.scatter(numpy.linspace(0,150,num=150),petal_length,color='orange') plt.show()