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SGDClassifier#
Show the boundary computed by a SGDClassifier.
import numpy as np
import matplotlib.pyplot as plt
from sklearn.linear_model import SGDClassifier
from sklearn.datasets import make_blobs
def plot_sgd_separator():
# we create 50 separable points
X, Y = make_blobs(n_samples=50, centers=2,
random_state=0, cluster_std=0.60)
# fit the model
clf = SGDClassifier(loss="hinge", alpha=0.01,
max_iter=200, fit_intercept=True)
clf.fit(X, Y)
# plot the line, the points, and the nearest vectors to the plane
xx = np.linspace(-1, 5, 10)
yy = np.linspace(-1, 5, 10)
X1, X2 = np.meshgrid(xx, yy)
Z = np.empty(X1.shape)
for (i, j), val in np.ndenumerate(X1):
x1 = val
x2 = X2[i, j]
p = clf.decision_function([[x1, x2]])
Z[i, j] = p[0]
levels = [-1.0, 0.0, 1.0]
linestyles = ['dashed', 'solid', 'dashed']
colors = 'k'
ax = plt.axes()
ax.contour(X1, X2, Z, levels, colors=colors, linestyles=linestyles)
ax.scatter(X[:, 0], X[:, 1], c=Y, cmap=plt.cm.Paired)
ax.axis('tight')
plot_sgd_separator()
Total running time of the script: ( 0 minutes 0.624 seconds)