# Plot the support vectors in LinearSVC#

Unlike SVC (based on LIBSVM), LinearSVC (based on LIBLINEAR) does not provide the support vectors. This example demonstrates how to obtain the support vectors in LinearSVC.

```import matplotlib.pyplot as plt
import numpy as np

from sklearn.datasets import make_blobs
from sklearn.inspection import DecisionBoundaryDisplay
from sklearn.svm import LinearSVC

X, y = make_blobs(n_samples=40, centers=2, random_state=0)

plt.figure(figsize=(10, 5))
for i, C in enumerate([1, 100]):
# "hinge" is the standard SVM loss
clf = LinearSVC(C=C, loss="hinge", random_state=42).fit(X, y)
# obtain the support vectors through the decision function
decision_function = clf.decision_function(X)
# we can also calculate the decision function manually
# decision_function = np.dot(X, clf.coef_[0]) + clf.intercept_[0]
# The support vectors are the samples that lie within the margin
# boundaries, whose size is conventionally constrained to 1
support_vector_indices = np.where(np.abs(decision_function) <= 1 + 1e-15)[0]
support_vectors = X[support_vector_indices]

plt.subplot(1, 2, i + 1)
plt.scatter(X[:, 0], X[:, 1], c=y, s=30, cmap=plt.cm.Paired)
ax = plt.gca()
DecisionBoundaryDisplay.from_estimator(
clf,
X,
ax=ax,
grid_resolution=50,
plot_method="contour",
colors="k",
levels=[-1, 0, 1],
alpha=0.5,
linestyles=["--", "-", "--"],
)
plt.scatter(
support_vectors[:, 0],
support_vectors[:, 1],
s=100,
linewidth=1,
facecolors="none",
edgecolors="k",
)
plt.title("C=" + str(C))
plt.tight_layout()
plt.show()
```

Total running time of the script: (0 minutes 0.258 seconds)

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