import matplotlib.pyplot as plt
import numpy as np

# create an array of x-values
x = np.arange(-3, 3, 0.01)

# see just how many values of x we just created
print len(x)

# calculate an array of y values as a function of x-values
y = (x-2)*(x+2)*(x-1)

# plot the quadratic function of y as a function of x
#
# first, create a figure window
fig1 = plt.figure()

#
# next, plot y as a function of x
plt.plot(x, y)

#
# annotate the plot with grid lines, a title, and axis labels
plt.title('My very first plot in Python. Yipee!!!')
plt.grid(True)
plt.xlabel('Input values (x)')
plt.ylabel('Output Values (y)')

#
# finally, "show" the plot in the figure window
plt.show()