Basic Python Project • Is It Raining?

Learning python? It’s an incredible programming language to have in your tool belt.

This project is inspired by an early example from Automate The Boring Stuff with Python.

Flow Control

This python project is to impliment this flow chart:

Taken from chapter 2, there’s a few things to digest, see the code step by step in Python Tutor.

Let’s write the steps is psuedoe code:

1. Ask if it’s raining?
2. If no, go outside.
3. If yes, ask if there’s an umbrella?
4. If umbrella no, wait and ask if raining again.
5. If umbrella yes, go outside.

While Loop

Let’s start with the outside variable and it’s while loop.

outside = False
while outside == False:
		# Other code goes here.
print('Go outside.')
exit()

As all paths lead to outside, it makes sense for the program to check if the user can go outside or not.

As long as outside is set to False, the user isn’t able to go out. But once other conditions are met and outside is True, then the program ends.

Input Validation

Let’s make a simple input validation when asking if there’s rain or not. This way the user can’t put in anything but what is expected.

While rain isn’t equal to y or n, continue asking the same question.

rain = 0
while (rain != 'y' or rain != 'n'):
	rain = input('Rain? y/n ')
        break
if rain == 'y':
	# More code goes here
elif rain == 'n':
	outside = True

We’ll use this same input validation for our other questions that require user input.

If there is rain, the program will continue asking questions. But if there’s no rain, then outside is set to True and will break the original while loop.

If Else Statements

Let’s add the last variable, umbrella.

umbrella = 0
if rain == 'y':
    print('Get an umbrella.')
    while (umbrella != 'y' or umbrella != 'n'):
        umbrella = input('Umbrella? y/n ')
        break
    if umbrella == 'n':
        print('Wait a while.')
    elif umbrella == 'y':
        outside = True
elif rain == 'n':
    outside = True 

Depending on the users input yes or no, either it will tell them to wait and then go back to the rain question or it will end the main while loop.

Failed Attempts

Just for a bit of fun, here are two of my failed attempts on the road to figuring out this program.

Version 2:

rain = input('Is it raining? y/n ')
while rain == 'y':
    print('
    if rain == 'n':
        print('Go outside!')
    else:
        break

Version 1:

raining = input('Is it raining? y/n ')
if raining == 'y':
    print('It\\'s raining!')
    umbrella = input('Do you have an umbrella? y/n ')
    if umbrella == 'n':
        print('Wait a while.')
        print('Time passes...')
        raining = input('Is it raining? y/n ')
        if raining == 'y':
            print('Wait a while, again.')
        else:
                print('Go outside.')
    else:
        print('Go outside.')
else:
    print('''It\\'s not raining!
    
    Go outisde!''')

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Happy Hacking.