def test_rfe():
generator = check_random_state(0)
iris = load_iris()
X = np.c_[iris.data, generator.normal(size=(len(iris.data), 6))]
X_sparse = sparse.csr_matrix(X)
y = iris.target
# dense model
clf = SVC(kernel="linear")
rfe = RFE(estimator=clf, n_features_to_select=4, step=0.1)
rfe.fit(X, y)
X_r = rfe.transform(X)
clf.fit(X_r, y)
assert len(rfe.ranking_) == X.shape[1]
# sparse model
clf_sparse = SVC(kernel="linear")
rfe_sparse = RFE(estimator=clf_sparse, n_features_to_select=4, step=0.1)
rfe_sparse.fit(X_sparse, y)
X_r_sparse = rfe_sparse.transform(X_sparse)
assert X_r.shape == iris.data.shape
assert_array_almost_equal(X_r[:10], iris.data[:10])
assert_array_almost_equal(rfe.predict(X), clf.predict(iris.data))
assert rfe.score(X, y) == clf.score(iris.data, iris.target)
assert_array_almost_equal(X_r, X_r_sparse.toarray())
for break_ties, title, ax in zip((False, True), titles, sub.flatten()):
svm = SVC(kernel="linear",
C=1,
break_ties=break_ties,
decision_function_shape='ovr').fit(X, y)
xlim = [X[:, 0].min(), X[:, 0].max()]
ylim = [X[:, 1].min(), X[:, 1].max()]
xs = np.linspace(xlim[0], xlim[1], 1000)
ys = np.linspace(ylim[0], ylim[1], 1000)
xx, yy = np.meshgrid(xs, ys)
pred = svm.predict(np.c_[xx.ravel(), yy.ravel()])
colors = [plt.cm.Accent(i) for i in [0, 4, 7]]
points = ax.scatter(X[:, 0], X[:, 1], c=y, cmap="Accent")
classes = [(0, 1), (0, 2), (1, 2)]
line = np.linspace(X[:, 1].min() - 5, X[:, 1].max() + 5)
ax.imshow(-pred.reshape(xx.shape),
cmap="Accent",
alpha=.2,
extent=(xlim[0], xlim[1], ylim[1], ylim[0]))
for coef, intercept, col in zip(svm.coef_, svm.intercept_, classes):
line2 = -(line * coef[1] + intercept) / coef[0]
ax.plot(line2, line, "-", c=colors[col[0]])
ax.plot(line2, line, "--", c=colors[col[1]])