Created
December 29, 2018 16:18
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import numpy as np | |
import matplotlib.pyplot as plt | |
from matplotlib.colors import ListedColormap | |
def plot_decision_regions(X, y, classifier, title=None, test_idx=None, resolution=0.02): | |
markers = ('s', 'x', 'o', '^', 'v') | |
colors = ('red', 'blue', 'lightgreen', 'gray', 'cyan') | |
cmap = ListedColormap(colors[:len(np.unique(y))]) | |
x1_min, x1_max = X[:, 0].min() - 1, X[:, 0].max()+1 | |
x2_min, x2_max = X[:, 1].min() - 1, X[:, 1].max()+1 | |
xx1, xx2 = np.meshgrid(np.arange(x1_min, x1_max, resolution), | |
np.arange(x2_min, x2_max, resolution)) | |
Z = classifier.predict(np.array([xx1.ravel(), xx2.ravel()]).T) | |
Z[Z> .5] = 1 | |
Z[Z<=.5] = 0 | |
Z = Z.reshape(xx1.shape) | |
plt.figure(figsize=(8, 8)) | |
plt.contourf(xx1, xx2, Z, alpha=0.4, cmap=cmap) | |
plt.xlim(xx1.min(), xx1.max()) | |
plt.ylim(xx2.min(), xx2.max()) | |
if title: | |
plt.title(title) | |
for idx, cl in enumerate(np.unique(y)): | |
plt.scatter(x=X[y == cl, 0], y=X[y == cl, 1], alpha=0.8, | |
c=cmap(idx), marker=markers[idx], label=cl) | |
if test_idx: | |
X_t, y_t = X[test_idx, :], y[test_idx] | |
plt.scatter(X_t[:, 0], X_t[:, 1], c='black', alpha=1.0, | |
linewidths=2, marker='|', s=55, label='test set') |
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