Piecewise Function in Python

import numpy as np
import matplotlib.pyplot as plt

def fun(x):
  #This is where all the info on the function goes
	if x < 28:
		return 100000*x - 2721000
	else:
		return 79000

vfun = np.vectorize(fun)

x = np.linspace(27,29)
y = vfun(x)

plt.axis([27,29,-25000,90000])
plt.plot(x,y,'-')
plt.show()

numpy's piecewise method also works well for ploting
piecewise functions

Is there anyways to avoid the vertical lines between each sections of x?