# p.40のコードのデータ読み込み部分をirisに変えただけ
from sklearn.datasets import load_iris
from sklearn.model_selection import train_test_split
from sklearn.neighbors import KNeighborsClassifier
import matplotlib.pyplot as plt
iris = load_iris()
X_train, X_test, y_train, y_test = train_test_split(
iris.data, iris.target, stratify=iris.target, random_state=0)
training_accuracy = []
test_accuracy = []
neighbors_settings = range(1, 30)
for n_neighbors in neighbors_settings:
clf = KNeighborsClassifier(n_neighbors=n_neighbors)
clf.fit(X_train, y_train)
training_accuracy.append(clf.score(X_train, y_train))
test_accuracy.append(clf.score(X_test, y_test))
plt.plot(neighbors_settings, training_accuracy, label="training accuracy")
plt.plot(neighbors_settings, test_accuracy, label="test accuracy")
plt.ylabel("Accuracy")
plt.xlabel("n_neighbors")
plt.legend()
plt.show()