FLD.py

import numpy as np
import matplotlib.pyplot as plt

def __main__():
    x_train = [[10, 50], [20, 30], [25, 30], [20, 60], [15, 70], [40, 40], [30, 45], [20, 45], [40, 30], [7, 35]]
    x_train = [x + [1] for x in x_train]
    x_train = np.array(x_train)
    y_train = np.array([-1, 1, 1, -1, -1, 1 ,1, -1, 1, -1])

    pt = np.sum([x * y for x, y in zip(x_train, y_train)], axis = 0) # sum xi(transp) * yi
    xxt = np.sum([np.outer(x, x) for x in x_train], axis = 0) # xi * xi(transp)
    w = np.dot(pt, np.linalg.inv(xxt))
    print(w)

    line_x = list(range(max(x_train[:, 0])))
    line_y = [-x * w[0] / w[1] - w[2] for x in line_x]

    x_0 = x_train[y_train == 1] 
    x_1 = x_train[y_train == -1]

    plt.scatter(x_0[:, 0], x_0[:, 1], color = 'red')
    plt.scatter(x_1[:, 0], x_1[:, 1], color = 'blue')
    plt.plot(line_x, line_y, color = 'green')

    plt.xlim([0, 45])
    plt.ylim([0, 75])
    plt.ylabel('length')
    plt.xlabel('width')
    plt.grid(True)
    plt.show()


if __name__ == '__main__':
    __main__()