This is a code problem for Python 3.5.2 using John Zelle's graphics.py:

I have spent a good amount of time looking for the answer here, but just can not figure it out. The function undraw() exists just like getMouse(). But it seems like it do not work for the plot() command, only the draw() command. What am I doing wrong? And how can I keep the window open, but erase the previous the plot before the next one is drawn?

pdf documentation for the functions of graphics:

    http://mcsp.wartburg.edu/zelle/python/graphics/graphics.pdf

win = GraphWin("Plot",500,500) # Creates a windowfor m in range(0,j): # Loop for each function# Randomizes a color for each functioncolor = random.choice( ['red','black','green','yellow','pink','blue'] )for h in range(0,t): # Loop for each pair of values "x,y"# Find points and plot each point in winwin.plot(axis[h],points[m][h],color)win.getMouse() # Pause before clickingwin.undraw() # AttributeError: 'GraphWin' object has no attribute 'undraw'

The first issue is that undraw() is a method of GraphicsObject, not GraphWin, so win.undraw() is simply incorrect.

The second issue is that plot() is a low level pixel setting method that does not keep track of what it did at the Zelle Graphics level, unlike objects that are drawn.

However, the underpinning is Tkinter which does keep track of objects that it draws, and GraphWin is a subclass of Canvas, so you can do:

win = GraphWin("Plot", 500, 500) # Creates a windowfor m in range(j):  # Loop for each functioncolor = random.choice(['red', 'black', 'green', 'yellow', 'pink', 'blue']) # Randomizes a color for each functionfor h in range(t):  # Loop for each pair of values "x, y"win.plot(axis[h], points[m][h], color) # Find points and plot each point in winwin.getMouse()  # Pause before clickingwin.delete("all")  # Clear out old plot