jupyternotebooks.py

#Practice Notebook: Methods and Classes
The code below defines an Elevator class. The elevator has a current floor, it also has a top and a bottom floor that are the minimum and maximum floors it can go to. Fill in the blanks to make the elevator go through the floors requested.

class Elevator:
    def __init__(self, bottom, top, current):
        self.bottom = bottom
        self.top = top
        self.current = current
        """Initializes the Elevator instance."""
        pass
​
    def up(self):
​
        if self.current >= self.top:
            self.current = self.top
        else:
            self.current += 1
        """Makes the elevator go up one floor."""
        pass
    def down(self):
        if self.current <= self.bottom:
            self.bottom = self.bottom
        else:
            self.current -=1
        """Makes the elevator go down one floor."""
        pass
    def go_to(self, floor):
        self.current = floor
        """Makes the elevator go to the specific floor."""
        pass
    def __str__(self):
        return "Current floor {}".format(self.current)
​
elevator = Elevator(-1, 10, 0)


This class is pretty empty and doesn't do much. To test whether your Elevator class is working correctly, run the code blocks below.

elevator.up() 
elevator.current #should output 1
0


elevator.down() 
elevator.current #should output 0
-1


elevator.go_to(10) 
elevator.current #should output 10
10


If you get a NameError message, be sure to run the Elevator class definition code block first. If you get an AttributeError message, be sure to initialize self.current in your Elevator class.

Once you've made the above methods output 1, 0 and 10, you've successfully coded the Elevator class and its methods. Great work!

For the up and down methods, did you take into account the top and bottom floors? Keep in mind that the elevator shouldn't go above the top floor or below the bottom floor. To check that out, try the code below and verify if it's working as expected. If it's not, then go back and modify the methods so that this code behaves correctly.

# Go to the top floor. Try to go up, it should stay. Then go down.
elevator.go_to(10)
elevator.up()
elevator.down()
print(elevator.current) # should be 9
# Go to the bottom floor. Try to go down, it should stay. Then go up.
elevator.go_to(-1)
elevator.down()
elevator.down()
elevator.up()
elevator.up()
print(elevator.current) # should be 1
9
1


Now add the str method to your Elevator class definition above so that when printing the elevator using the print( ) method, we get the current floor together with a message. For example, in the 5th floor it should say "Current floor: 5"

elevator.go_to(5)
print(elevator)
Current floor 5


Remember, Python uses the default method, that prints the position where the object is stored in the computer’s memory. If your output is something like:

<main.Elevator object at 0x7ff6a9ff3fd0>

Then you will need to add the special str method, which returns the string that you want to print. Try again until you get the desired output, "Current floor: 5".

Once you have successfully produced the desired output, you are all done with this practice notebook. Awesome!