import numpy as np
import matplotlib.pyplot as plt
from sklearn.neighbors import KNeighborsRegressor
def make_dataset(n_samples=100):
rnd = np.random.RandomState(42)
x = np.linspace(-3, 3, n_samples)
y_no_noise = np.sin(4 * x) + x
y = y_no_noise + rnd.normal(size=len(x))
return x, y
def plot_regression_datasets():
fig, axes = plt.subplots(1, 3, figsize=(15, 5))
for n_samples, ax in zip([10, 100, 1000], axes):
x, y = make_dataset(n_samples)
ax.plot(x, y, 'o', alpha=.6)
def plot_kneighbors_regularization():
rnd = np.random.RandomState(42)
x = np.linspace(-3, 3, 100)
y_no_noise = np.sin(4 * x) + x
y = y_no_noise + rnd.normal(size=len(x))
X = x[:, np.newaxis]
fig, axes = plt.subplots(1, 3, figsize=(15, 5))
x_test = np.linspace(-3, 3, 1000)
for n_neighbors, ax in zip([2, 5, 20], axes.ravel()):
kneighbor_regression = KNeighborsRegressor(n_neighbors=n_neighbors)
kneighbor_regression.fit(X, y)
ax.plot(x, y_no_noise, label="true function")
ax.plot(x, y, "o", label="data")
ax.plot(x_test, kneighbor_regression.predict(x_test[:, np.newaxis]),
label="prediction")
ax.legend()
ax.set_title("n_neighbors = %d" % n_neighbors)
if __name__ == "__main__":
plot_kneighbors_regularization()
plt.show()
