分类
from sklearn.neighbors import KNeighborsClassifier as Knn
from sklearn.datasets import load_iris
from sklearn.model_selection import train_test_split
X, y = load_iris(return_X_y=True)
X_train, X_test, y_train, y_test = train_test_split(X, y, train_size=0.2)
sk_knn = Knn(n_neighbors=5)
sk_knn.fit(X=X_train, y=y_train)
y_pred = sk_knn.predict(X=X_test)
acc = (y_pred == y_test).mean()
print(acc)
回归
from sklearn.neighbors import KNeighborsRegressor as Knn
from sklearn.model_selection import train_test_split
from sklearn.datasets import fetch_california_housing
X, y = fetch_california_housing(return_X_y=True)
X_train, X_test, y_train, y_test = train_test_split(X, y, train_size=0.2)
sk_knn = Knn(n_neighbors=5)
sk_knn.fit(X=X_train, y=y_train)
y_pred = sk_knn.predict(X=X_test)
mse = ((y_pred - y_test) ** 2).mean()
print(mse)