#!/usr/bin/python


import numpy as np
import matplotlib.pyplot as plt


plt.rcParams['legend.fontsize'] = 10

fig = plt.figure ()
ax = fig.gca ()

data = np.array([
    [-2, 1],
    [-1,-1],
    [ 0, 1],
    [ 1,-1],
    [ 2, 1]
])
x, y = data.T

ax.set_xticks ([-2, -1, 1, 2])
ax.spines['left'].set_position ('center')
ax.spines['right'].set_position ('center')

ax.set_yticks ([-1, -0.5, 0.5, 1])
ax.spines['top'].set_position ('center')
ax.spines['bottom'].set_position ('center')

plt.scatter (x, y, label='$y=(-1)^{x}$')
ax.legend ()

plt.show ()