import matplotlib.pyplot as plt
import pandas as pd
import numpy as np
from sklearn.datasets import load_iris
from sklearn.decomposition import PCA
iris=load_iris()
X=iris.data
y=iris.target
X.shape

#调用PCA
pca=PCA(n_components=2)
pca=pca.fit(X)
X_dr=pca.transform(X)

#X_dr=PCA(2).fit_transform(X)另外一种方式

#如何实现把三种类型的鸢尾花显示在二维坐标上呢
plt.figure()
plt.scatter(X_dr[y==0,0],X_dr[y==0,1],color="red",label=iris.target_names[0])
plt.scatter(X_dr[y==1,0],X_dr[y==1,1],color="blue",label=iris.target_names[1])
plt.scatter(X_dr[y==2,0],X_dr[y==2,1],color="orange",label=iris.target_names[2])
plt.legend()
plt.show()