Develop Reference

Mathematic questions in python

Looking on for some guidance on how to write a python code
that executes the following:
The program will ask for math problems to solve.
The program will asks for the number of problems.
And asks for how many attempts for each problem.
For example:
Enter amount of programs: 4
Enter amount of attempts: 5
what is: 4x3 =?
Your answer: 16
and so goes on to another attempt if wrong if correct moves onto another problem, just like before and exits when attempts or problems are finished.
I have this code but I want to it only do multiplication ONLY and would like to know how to integrate how to put additional code to limit how many time one can solve the question and how many questions it asks
import random
def display_separator():
print("-" * 24)
def get_user_input():
user_input = int(input("Enter your choice: "))
while user_input > 5 or user_input <= 0:
print("Invalid menu option.")
user_input = int(input("Please try again: "))
else:
return user_input
def get_user_solution(problem):
print("Enter your answer")
print(problem, end="")
result = int(input(" = "))
return result
def check_solution(user_solution, solution, count):
if user_solution == solution:
count = count + 1
print("Correct.")
return count
else:
print("Incorrect.")
return count
def menu_option(index, count):
number_one = random.randrange(1, 21)
number_two = random.randrange(1, 21)
problem = str(number_one) + " + " + str(number_two)
solution = number_one + number_two
user_solution = get_user_solution(problem)
count = check_solution(user_solution, solution, count)
def display_result(total, correct):
if total > 0:
result = correct / total
percentage = round((result * 100), 2)
if total == 0:
percentage = 0
print("You answered", total, "questions with", correct, "correct.")
print("Your score is ", percentage, "%. Thank you.", sep = "")
def main():
display_separator()
option = get_user_input()
total = 0
correct = 0
while option != 5:
total = total + 1
correct = menu_option(option, correct)
option = get_user_input()
print("Exit the quiz.")
display_separator()
display_result(total, correct)
main()

As far as making sure you're only allowing multiplication problems, the following function should work.
def valid_equation(user_input):
valid = True
for char in user_input:
if not(char.isnumeric() or char == "*"):
valid = False
return valid
Then after each user_input you can run this function and it will return True if the only things in the users string are numbers and the * sign and False otherwise. Then you just need to check the return value with a if statement that tells the user that their input is invalid if it returns False. You can add more "or" operations to the if statement if you want to allow other things. Like if you want to allow spaces (or char == " ").
As far as limiting the number of times a user can try to answer, and limiting the number of questions asked, you just need to store the values the user enters when you ask them these numbers. From there you can do nested while loops for the main game.
i = 0
user_failed = False
while ((i < number_of_questions) and (user_failed == False)):
j = 0
while ((j < number_of_attempts) and (user_correct == False)):
#Insert question asking code here
#In this case if the user is correct it would make user_correct = True.
j += 1
if j == number_of_attempts:
user_failed = True
i += 1
So in this situation, the outer while loop will iterate until all of the questions have been asked, or the user has failed the game. The inner loop will iterate until the user has used up all of their attempts for the question, or the user has passed the question. If the loop exits because the user used up all of their attempts, the for loop will trigger making the user lose and causing the outer loop to stop executing. If it does not it will add one to i, saying that another question has been asked, and continue.
These are just some ideas on how to solve the kinds of problems you're asking about. I'll leave the decision on how exactly to implement something like this into your code, or if you decide to change parts of your code to better facilitate systems like this up to you. Hope this helps and have a great one!

Python. Variable in while loop not updating.

I'm very new to programming and I've encountered a problem with a basic guessing game I've been writing.
x is a random number generated by the computer. The program is supposed to compare the absolute value of (previous_guess - x) and the new guess minus x and tell the user if their new guess is closer or further away.
But the variable previous_guess isn't updating with the new value.
Any help would be appreciated.
Here is the code so far:
###Guessing Game
import random
n = 100
x = random.randint(1,n)
print("I'm thinking of a number between 1 and ", n)
##print(x) ## testing/cheating.
count = 0
while True:
previous_guess = 0 # Should update with old guess to be compared with new guess
guess = int(input("Guess the number, or enter number greater that %d to quit." % n))
count += 1
print(previous_guess)
print("Guesses: ", count)
if guess > n:
print("Goodbye.")
break
elif count < 2 and guess != x:
print("Unlucky.")
previous_guess = guess #####
elif count >= 2 and guess != x:
if abs(guess - x) < abs(previous_guess - x):
previous_guess = guess #####
print("Getting warmer...")
else:
previous_guess = guess #####
print("Getting colder...")
elif guess == x:
print("You win! %d is correct! Guessed in %d attempt(s)." % (x,count))
break

Your previous guess is being reinitialized every time you loop. This is a very common error in programming so it's not just you!
Change it to:
previous_guess = 0
while True:
#Rest of code follows
Things you should be thinking about when stuff like this shows up.
Where is your variable declared?
Where is your variable initialized?
Where is your variable being used?
If you are unfamiliar with those terms it's okay! Look em up! As a programmer you HAVE to get good at googling or searching documentation (or asking things on stack overflow, which it would appear you have figured out).
Something else that is critical to coding things that work is learning how to debug.
Google "python debug tutorial", find one that makes sense (make sure that you can actually follow the tutorial) and off you go.

You're resetting previous_guess to 0 every time the loop begins again, hence throwing away the actual previous guess. Instead, you want:
previous_guess = 0
while True:
guess = ....

You need to initialize previous guess before while loop. Otherwise it will be initialized again and again.
You have updated previous guess in multiple places. You can make it simpler:
import random
n = 100
x = random.randint(1,n)
print("I'm thinking of a number between 1 and ", n)
##print(x) ## testing/cheating.
count = 0
previous_guess = 0 # Should update with old guess to be compared with new guess
while True:
guess = int(input("Guess the number, or enter number greater that %d to quit." % n))
count += 1
print(previous_guess)
print("Guesses: ", count)
if guess > n:
print("Goodbye.")
break
elif count < 2 and guess != x:
print("Unlucky.")
elif count >= 2 and guess != x:
if abs(guess - x) < abs(previous_guess - x):
print("Getting warmer...")
else:
print("Getting colder...")
elif guess == x:
print("You win! %d is correct! Guessed in %d attempt(s)." % (x,count))
break
previous_guess = guess #####

You need to initialize previous guess before while loop Otherwise it will be initialized again and again. You have to set the value of previous guess to x the computer generator and when you move on after loop you have to update the previous guess to next simply like this:
Add before while { previous_guess = x }
Add After While { previous_guess += x }
###Guessing Game
import random
n = 100
x = random.randint(1,n)
print("I'm thinking of a number between 1 and ", n)
##print(x) ## testing/cheating.
count = 0
previous_guess = x
while True:
# Should update with old guess to be compared with new guess
previous_guess += x
guess = int(input("Guess the number, or enter number greater that %d to quit." % n))
count += 1
print(previous_guess)
print("Guesses: ", count)
if guess > n:
print("Goodbye.")
break
elif count < 2 and guess != x:
print("Unlucky.")
previous_guess = guess #####
elif count >= 2 and guess != x:
if abs(guess - x) < abs(previous_guess - x):
previous_guess = guess #####
print("Getting warmer...")
else:
previous_guess = guess #####
print("Getting colder...")
elif guess == x:
print("You win! %d is correct! Guessed in %d attempt(s)." % (x,count))
break
Picture When u win
Picture When u loose

Calculating average from raw_input data in a while loop

Fellow python developers. I have a task which I can't seem to crack and my tutor is MIA. I need to write a program which only makes use of while loops, if, elif and else statements to:
Constantly ask the user to enter any random positive integer using int(raw_input())
Once the user enters -1 the program needs to end
the program must then calculate the average of the numbers the user has entered (excluding the -1) and print it out.
this what I have so far:
num = -1
counter = 1
anyNumber = int(raw_input("Enter any number: "))
while anyNumber > num:
anyNumber = int(raw_input("Enter another number: "))
counter += anyNumber
answer = counter + anyNumber
print answer
print "Good bye!"

Try the following and ask any question you might have
counter = 0
total = 0
number = int(raw_input("Enter any number: "))
while number != -1:
counter += 1
total += number
number = int(raw_input("Enter another number: "))
if counter == 0:
counter = 1 # Prevent division by zero
print total / counter

You need to add calculating average at the end of your code.
To do that, have a count for how many times the while loop runs, and divide the answer at the end by that value.
Also, your code is adding one to the answer each time because of the line - answer = counter + anyNumber, which will not result in the correct average. And you are missing storing the first input number, because the code continuously takes two inputs. Here is a fixed version:
num = -1
counter = 0
answer = 0
anyNumber = int(raw_input("Enter any number: "))
while anyNumber > num:
counter += 1
answer += anyNumber
anyNumber = int(raw_input("Enter another number: "))
if (counter==0): print answer #in case the first number entered was -1
else:
print answer/counter #print average
print "Good bye!"

There's another issue I think:
anyNumber = int(raw_input("Enter any number: "))
while anyNumber > num:
anyNumber = int(raw_input("Enter another number: "))
The value of the variable anyNumber is updated before the loop and at the beginning of the loop, which means that the first value you're going to enter is never going to be taken in consideration in the average.

A different solution, using a bit more functions, but more secure.
import numpy as np
numbers = []
while True:
# try and except to avoid errors when the input is not an integer.
# Replace int by float if you want to take into account float numbers
try:
user_input = int(input("Enter any number: "))
# Condition to get out of the while loop
if user_input == -1:
break
numbers.append(user_input)
print (np.mean(numbers))
except:
print ("Enter a number.")

You don't need to save total because if the number really big you can have an overflow. Working only with avg should be enough:
STOP_NUMBER = -1
new_number = int(raw_input("Enter any number: "))
count = 1
avg = 0
while new_number != STOP_NUMBER:
avg *= (count-1)/count
avg += new_number/count
new_number = int(raw_input("Enter any number: "))
count += 1

I would suggest following.
counter = input_sum = input_value = 0
while input_value != -1:
counter += 1
input_sum += input_value
input_value = int(raw_input("Enter any number: "))
try:
print(input_sum/counter)
except ZeroDivisionError:
print(0)
You can avoid using two raw_input and use everything inside the while loop.

There is another way of doing..
nums = []
while True:
num = int(raw_input("Enter a positive number or to quit enter -1: "))
if num == -1:
if len(nums) > 0:
print "Avg of {} is {}".format(nums,sum(nums)/len(nums))
break
elif num < -1:
continue
else:
nums.append(num)

Here's my own take on what you're trying to do, although the solution provided by #nj2237 is also perfectly fine.
# Initialization
sum = 0
counter = 0
stop = False
# Process loop
while (not stop):
inputValue = int(raw_input("Enter a number: "))
if (inputValue == -1):
stop = True
else:
sum += inputValue
counter += 1 # counter++ doesn't work in python
# Output calculation and display
if (counter != 0):
mean = sum / counter
print("Mean value is " + str(mean))
print("kthxbye")

In Python, How do I make my conditional if loop not execute if input is valid?

#Write a short program that will do the following
#Set a value your favorite number between 0 and 100
#Ask the user to guess your favorite number between 0 and 100
#Repeat until they guess that number and tell them how many tries it took
#If the value they guessed is not between 0 and 100
#tell the user invalid guess and do not count that as an attempt
My problem is that even if the user guesses a number between 0 and 100, it still prints out the "Invalid guess. Try again". How do I control my loop to skip past the print statement and question repeat if it's acceptable input(1-100)? Thanks in advance!
favoriteNumber = 7
attempts = 0
guess = raw_input("Guess a number between 0 and 100: ")
if (guess < 0) or (guess > 100):
print "Invalid guess. Try again"
guess = raw_input("Guess a number between 0 and 100: ")
attempts1 = str(attempts)
print "it took " + attempts1 + "attempts."

Use input and not raw_input,so you get integer and not string
favoriteNumber = 7
attempts = 0
while True:
guess = input("Guess a number between 0 and 100: ")
if (guess < 0) or (guess > 100):
attempts=attempts+1
print "Invalid guess. Try again"
else:
attempts=attempts+1
break
attempts1 = str(attempts)
print "it took " + attempts1 + " attempts."

In Python 2.7.10 it appears that if you do not convert a string to an integer, it accepts it but all rules that apply to numbers return false.
Here is a working example:
favoriteNumber = 7
attempts = 0
guess = raw_input("Guess a number between 0 and 100: ")
if (int(guess) < 0) or (int(guess) > 100):
print "Invalid guess. Try again"
guess = raw_input("Guess a number between 0 and 100: ")
attempts1 = str(attempts)
print "it took " + attempts1 + " attempts."
In Python 3.4 the original code yields an error where it tells you that it is a string instead of an integer. But, like Paul said you could put raw_input inside of an int() command.

you raw_input returns a string, which is always > 100. Cast it to a number with int(raw_input())

Need shorter/more elegant solution to python while loop

I'm a new programmer and I was struggling with a solution to this problem:
User Input with Loops and Conditionals. Use raw_input() to prompt for a number
between 1 and 100. If the input matches criteria, indicate so on the screen and exit.
Otherwise, display an error and re-prompt the user until the correct input is received.
My last attempt finally worked but I'm interested to know your more elegant solutions, my memory appreciates all of your input :P
n = int(input("Type a number between 1 and 100 inclusive: "))
if 1 <= n <= 100:
print("Well done!" + " The number " + str(n) + " satisfies the condition.")
else:
while (1 <= n <= 100) != True:
print("Error!")
n = int(input("Type a number between 1 and 100: "))
else:
print ("Thank goodness! I was running out of memory here!")

You can simplify the code, using a single loop:
while True:
n = int(input("Type a number between 1 and 100 inclusive: "))
if 1 <= n <= 100:
print("Well done!" + " The number " + str(n) + " satisfies the condition.")
print ("Thank goodness! I was running out of memory here!")
break # if we are here n was in the range 1-100
print("Error!") # if we are here it was not
You just print the output and break if the user enters a correct number or print("Error!") will be printed and the user will be asked again.
On a side note, if you are using python2, input is the equivalent to eval(raw_input()), if you are taking user input you should generally use raw_input as per the instructions in your question.