While Loop With Yes/no Input (python)

I am building a script to plot smooth and plot values. However, I am having trouble getting the yes/no function to control the while loop. I am setting the while condition equal to

Solution 1:

Try:

defyes_or_no(question):
    reply = str(input(question+' (y/n): ')).lower().strip()
    if reply[0] == 'y':
        return1elif reply[0] == 'n':
        return0else:
        return yes_or_no("Please Enter (y/n) ")

print("started")
whileTrue:
    # DRAW PLOT HERE;print("See plot....")
    if(yes_or_no('Do you like the plot')):
        breakprint("done")

Best to keep function definition separate from loop for clarity. Also, otherwise it will be read in every loop wasting resources.

Output:

$ python ynquestion.py 
started
See plot....
Do you like the plot (y/n): n
See plot....
Do you like the plot (y/n): N 
See plot....
Do you like the plot (y/n): NO
See plot....
Do you like the plot (y/n): No
See plot....
Do you like the plot (y/n): no
See plot....
Do you like the plot (y/n): yesdone
$

Solution 2:

You should definitely look at some tutorials about "how to code" in general. There are several "misconceptions". However, here is a cleaner version:

import matplotlib.pyplot as plt
import numpy

defbunch_of_math():
    ...

defplotting():
    ...

# move this into the loop in case you want to calc and plot# new stuff every iteration
bunch_of_math()
plotting()

print("start")

whileTrue:
    reply = str(input(question+' (y/n): ')).lower().strip()
    if reply == 'y':
        breakelif reply == 'n':
        breakelse:
        print("please select (y/n) only")
        continueprint("done")

It is bad style to declare a function inside a loop, especially if you do not need this. Your code would re-create the function at each iteration, which you would only need if you somehow alter your function in each iteration.

reply[0] = 'n' means that you want to access the list or array (a container data structure) reply with the index 0 and write 'n' there. You have not initialized such a container. Additionally, you do not need a container at all, because you do not store each user input. You just care for the most recent answer of you user -> a variable is enough.

if reply[0] == 'y':
    return1if reply[0] == 'n':
    return0else:
    return yes_or_no("Please Enter (y/n) ")

You have two if conditions after another: Python would check for == 'y' and then always check again for == 'n'. You need to use elif to declare an else-if condition, otherwise you waste resources or ran into unexpected behavior. Additionally, you are never using the return values. The while-loop just exits with a break statement, because it is a loop. Thus, your return statements are pointless.

Solution 3:

defyes_or_no(question):
    whileTrue:
        answer = input(question + ' (y/n): ').lower().strip()
        if answer in ('y', 'yes', 'n', 'no'):
            return answer in ('y', 'yes')
        else:
            print('You must answer yes or no.')

yes_or_no('Do you like the plot?')

Solution 4:

you can't intialize an index of an array.

change reply[0] = 'n' to reply = 'n'

Solution 5:

First error - You never defined reply, so how do you index that string?

whileTrue:
    reply[0] = 'n'# What is reply??

Also break is outside the loop, which should be a SyntaxError.

---

Second error - You defined a loop, but never changed the value reply in the loop itself. Plus, yes_or_no() is called outside of the loop (but it never breaks the loop, only returns from the function).

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You're having some misunderstanding about how functions work. They are separate code blocks, not intended to be nested within your other logic.

defyes_or_no(question):
    whileTrue:
        reply = input(question + ' (y/n): ')).lower().strip()
        if reply.startswith('y'):
            breakprint("started")
yes_or_no('Do you like the plot')
print("done")

Or, probably a more readable version

def yes_or_no(question):
    return input(question + ' (y/n): ')).lower().strip()

print("started")
question = 'Do you like the plot?'
like_plot = yes_or_no(question).startswith('y')
while not like_plot:
    like_plot = yes_or_no(question).startswith('y')
print("done")