import numpy as np
import matplotlib.pyplot as plt

import numpy.random as npr

x = np.linspace(0, 4, 21)
y = np.exp(-x)
xe = np.abs(0.08 * npr.randn(len(x)))
ye = np.abs(0.1 * npr.randn(len(y)))
plt.errorbar(x, y, fmt="bo", lw=2, xerr=xe, yerr=ye, ecolor="r", elinewidth=1)
plt.show()