import matplotlib.pyplot as plt
import numpy as np
y = np.array([50, 25, 25, 15])
myexp = [0, 0, 0.2, 0]
mylabels = ["Москва", "Санкт-Петербург", "Екатеринбург", "Пермь"]
mycolors = ["lime", "green", "brown", "yellow"]
plt.pie(y, labels=mylabels, explode=myexp, shadow=True, colors=mycolors)
plt.legend(title="Население городов: ")
plt.show()