# Sparsity Example: Fitting only features 1 and 2¶

Features 1 and 2 of the diabetes-dataset are fitted and plotted below. It illustrates that although feature 2 has a strong coefficient on the full model, it does not give us much regarding y when compared to just feature 1.

# Code source: Gaël Varoquaux
# Modified for documentation by Jaques Grobler


First we load the diabetes dataset.

from sklearn import datasets
import numpy as np

indices = (0, 1)

X_train = X[:-20, indices]
X_test = X[-20:, indices]
y_train = y[:-20]
y_test = y[-20:]


Next we fit a linear regression model.

from sklearn import linear_model

ols = linear_model.LinearRegression()
_ = ols.fit(X_train, y_train)


Finally we plot the figure from three different views.

import matplotlib.pyplot as plt

def plot_figs(fig_num, elev, azim, X_train, clf):
fig = plt.figure(fig_num, figsize=(4, 3))
plt.clf()
ax = fig.add_subplot(111, projection="3d", elev=elev, azim=azim)

ax.scatter(X_train[:, 0], X_train[:, 1], y_train, c="k", marker="+")
ax.plot_surface(
np.array([[-0.1, -0.1], [0.15, 0.15]]),
np.array([[-0.1, 0.15], [-0.1, 0.15]]),
clf.predict(
np.array([[-0.1, -0.1, 0.15, 0.15], [-0.1, 0.15, -0.1, 0.15]]).T
).reshape((2, 2)),
alpha=0.5,
)
ax.set_xlabel("X_1")
ax.set_ylabel("X_2")
ax.set_zlabel("Y")
ax.w_xaxis.set_ticklabels([])
ax.w_yaxis.set_ticklabels([])
ax.w_zaxis.set_ticklabels([])

# Generate the three different figures from different views
elev = 43.5
azim = -110
plot_figs(1, elev, azim, X_train, ols)

elev = -0.5
azim = 0
plot_figs(2, elev, azim, X_train, ols)

elev = -0.5
azim = 90
plot_figs(3, elev, azim, X_train, ols)

plt.show()


Total running time of the script: ( 0 minutes 0.155 seconds)

Gallery generated by Sphinx-Gallery