plot_xy_pairs.py

#  Make the matplotlib and matplotlib.pyplot modules available
import matplotlib
matplotlib.use("Agg")
import matplotlib.pyplot as plt

#  Initialize x_values and y_values to be empty lists
x_values = list()
y_values = list()

done = False
#  Read input from the user until they enter an empty string
while not done:
    line = input('Enter an x,y pair: ')
    
    #  Test to see if the user entered the empty string.  If not
    if line != '':
        #  Break up the current line of input at the “,” location
        parts = line.split(',')
        #  Add the part to the left of the comma to x values
        #  Add the part to the right of the comma y values
        x_values.append(int(parts[0]))
        y_values.append(int(parts[1]))
    else:
        done = True

print (x_values)
print (y_values)


#  Create a plot from the two lists of values
plt.plot(x_values, y_values, 'ro')

#  Save the plot to a file for later viewing
plt.savefig('scatter.png')