v Plot The Support Vector Classifier's Hyperplane - Machine Learning

Plot The Support Vector Classifier's Hyperplane

Preliminaries

# Load libraries
from sklearn.svm import LinearSVC
from sklearn import datasets
from sklearn.preprocessing import StandardScaler
import numpy as np
from matplotlib import pyplot as plt

Load Iris Flower Data

# Load data with only two classes and two features
iris = datasets.load_iris()
X = iris.data[:100,:2]
y = iris.target[:100]

Standardize Features

# Standarize features
scaler = StandardScaler()
X_std = scaler.fit_transform(X)

Train Support Vector Classifier

# Create support vector classifier
svc = LinearSVC(C=1.0)

# Train model
model = svc.fit(X_std, y)

Plot Decision Boundary Hyperplane

In this visualization, all observations of class 0 are black and observations of class 1 are light gray. The hyperplane is the decision-boundary deciding how new observations are classified. Specifically, any observation above the line will by classified as class 0 while any observation below the line will be classified as class 1.

# Plot data points and color using their class
color = ['black' if c == 0 else 'lightgrey' for c in y]
plt.scatter(X_std[:,0], X_std[:,1], c=color)

# Create the hyperplane
w = svc.coef_[0]
a = -w[0] / w[1]
xx = np.linspace(-2.5, 2.5)
yy = a * xx - (svc.intercept_[0]) / w[1]

# Plot the hyperplane
plt.plot(xx, yy)
plt.axis("off"), plt.show();

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