import numpy as np
import matplotlib.pyplot as plt
try:
import probml_utils as pml
except ModuleNotFoundError:
%pip install -qq git+https://github.com/probml/probml-utils.git
import probml_utils as pml
err = np.linspace(-3.0, 3.0, 60)
L1 = abs(err)
L2 = err**2
delta = 1.5
ind = abs(err) <= delta
huber = np.multiply(0.5 * ind, (err**2)) + np.multiply((1 - ind), (delta * (abs(err) - delta / 2)))
vapnik = np.multiply(ind, 0) + np.multiply((1 - ind), (abs(err) - delta))
plt.plot(err, L1, "k-.")
plt.plot(err, L2, "r-")
plt.plot(err, vapnik, "b:")
plt.plot(err, huber, "g-.")
plt.legend(["L1", "L2", "$ϵ$-insensitive", "huber"])
plt.ylim((-0.5, 5))
pml.savefig("Huber.pdf")
plt.show()
