決定境界の描画ライブラリ

mlxtendのplot_decision_regionsを使う。

from sklearn.model_selection import train_test_split
from sklearn.decomposition import PCA, KernelPCA
from sklearn import datasets
from sklearn.svm import SVC
from mlxtend.plotting import plot_decision_regions

iris = datasets.load_iris()
X = iris.data
y = iris.target
X_train, X_test, y_train, y_test = train_test_split(X,y)
pca = PCA(n_components = 2)
X_train_pca = pca.fit_transform(X_train) 
X_test_pca = pca.fit_transform(X_test)
clf = SVC()
clf.fit(X_train_pca, y_train)
plot_decision_regions(X_test_pca,y_test,clf)