如何绘制不同颜色的 3D PCA？

Posted 2023-03-12

【中文标题】如何绘制不同颜色的 3D PCA？

【英文标题】：How to plot 3D PCA with different colors?

【发布时间】：2021-03-22 07:23:48

【问题描述】：

让我们获取以下数据：

 import numpy as np
from sklearn.datasets import load_breast_cancer
import pandas as pd
from sklearn.decomposition import PCA
from sklearn import datasets
from sklearn.preprocessing import StandardScaler

让我们考虑数据

data = load_breast_cancer()
X = data.data
y = data.target
sc = StandardScaler()

我想用 3 个分量绘制 PCA 的 3D 图，但我只能为前两个分量绘制。

我目前的工作

scaler=StandardScaler()
scaler.fit(X) 
X_scaled=scaler.transform(X)
pca=PCA(n_components=3)
pca.fit(X_scaled) 
X_pca=pca.transform(X_scaled) 
ex_variance=np.var(X_pca,axis=0)
ex_variance_ratio = ex_variance/np.sum(ex_variance)
ex_variance_ratio


Xax=X_pca[:,0]
Yax=X_pca[:,1]
cdict=0:'red',1:'green'
labl=0:'Malignant',1:'Benign'
marker=0:'*',1:'o'
alpha=0:.3, 1:.5
fig,ax=plt.subplots(figsize=(7,5))
fig.patch.set_facecolor('white')
for l in np.unique(y):
 ix=np.where(y==l)
 ax.scatter(Xax[ix],Yax[ix],c=cdict[l],s=40,
           label=labl[l],marker=marker[l],alpha=alpha[l])
# for loop ends
plt.xlabel("First Principal Component",fontsize=14)
plt.ylabel("Second Principal Component",fontsize=14)
plt.legend()
plt.show()

在输出中我们得到：

您知道如何为第三个主要组件执行此操作吗？当然它应该是 3D，但我不知道该怎么做......

【参考方案1】：

其实很简单-

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt

from mpl_toolkits.mplot3d import Axes3D
from sklearn.datasets import load_breast_cancer
from sklearn.decomposition import PCA
from sklearn import datasets
from sklearn.preprocessing import StandardScaler
# %matplotlib notebook

data = load_breast_cancer()
X = data.data
y = data.target
sc = StandardScaler()

scaler = StandardScaler()
scaler.fit(X) 
X_scaled = scaler.transform(X)

pca = PCA(n_components=3)
pca.fit(X_scaled) 
X_pca = pca.transform(X_scaled) 

ex_variance=np.var(X_pca,axis=0)
ex_variance_ratio = ex_variance/np.sum(ex_variance)
ex_variance_ratio


Xax = X_pca[:,0]
Yax = X_pca[:,1]
Zax = X_pca[:,2]

cdict = 0:'red',1:'green'
labl = 0:'Malignant',1:'Benign'
marker = 0:'*',1:'o'
alpha = 0:.3, 1:.5

fig = plt.figure(figsize=(7,5))
ax = fig.add_subplot(111, projection='3d')

fig.patch.set_facecolor('white')
for l in np.unique(y):
 ix=np.where(y==l)
 ax.scatter(Xax[ix], Yax[ix], Zax[ix], c=cdict[l], s=40,
           label=labl[l], marker=marker[l], alpha=alpha[l])
# for loop ends
ax.set_xlabel("First Principal Component", fontsize=14)
ax.set_ylabel("Second Principal Component", fontsize=14)
ax.set_zlabel("Third Principal Component", fontsize=14)

ax.legend()
plt.show()

这就是你所追求的吗？

【讨论】：

你太棒了！正是我想要的！

谢谢，但您确实完成了大部分工作！ =)