Trying to learn Python. Been at this one for hours.
What I am trying to do is to enter a few numbers (for example 7, 4, 6, 10, & 2) and then print the maximum and minimum.
My code works perfectly for every number I enter that is 1-9. Once I hit 10 or higher it goes wonky.
It appears that it is reading 10 as a 1 with a zero attached to it and it says 10 is the minimum.
Where am I going wrong here?
.
The exercise is to enter a few numbers and then print the maximum and minimum. My code works perfectly for every number I enter that is 1-9. Once I hit 10 or higher it goes wonky and lists 10 as the minimum.
Where am I going wrong here?
.
largest = None
smallest = None
the_list = []
while True:
num = input('Enter a number or done: ')
#Handle the edge cases
if num == 'done' : break
if len(num) < 1 : break # Check for empty line
# Do the work
try :
number = int(num)
the_list.append(num)
except:
print("Invalid input")
#continue
print(the_list) # NOTE: This is new so I can see what is in the_list
for value in the_list:
if smallest is None:
smallest = value
elif value < smallest:
smallest = value
for the_num in the_list:
if largest is None:
largest = value
elif the_num > largest:
largest = value #the_num
print("Maximum is", largest)
print( "Minimum is", smallest)
The problem is that you are appending the string to the list, not the integer. That is, your list consists of the following right now (if you entered 2 and then 10:
the_list = ['2', '10']
Since strings are compared lexicographically, '10' is less than '2', because '1' is less than '2'. What you want to do is to append the integer.
try :
number = int(num)
the_list.append(number)
except:
print("Invalid input")
#continue
This way, you'll be comparing the numerical values of the numbers, and you'll get the correct answer!
You actually don't append number to the list but you append num to the list (a simple typo, I presume). Thus, you never append an int to the list but the str. Obviously, this will create problems later when you compare strings, such as:
>>> '10' < '3'
True
Change the_list.append(num) to the_list.append(number)
Another error is that in your second for loop you forgot to change value to the_num
Related
number = 0
number_list = []
while number != -1:
number = int(input('Enter a number'))
number_list.append(number)
else:
print(sum(number_list)/ len(number_list))
EDIT: Have found a simpler way to get the average of the list but if for example I enter '2' '3' '4' my program calculates the average to be 2 not 3. Unsure of where it's going wrong! Sorry for the confusion
Trying out your code, I did a bit of simplification and also utilized an if statement to break out of the while loop in order to give a timely average. Following is the snippet of code for your evaluation.
number_list = []
def average(mylist):
return sum(mylist)/len(mylist)
while True:
number = int(input('Enter a number: '))
if number == -1:
break
number_list.append(number)
print(average(number_list));
Some points to note.
Instead of associating the else statement with the while loop, I revised the while loop utilizing the Boolean constant "True" and then tested for the value of "-1" in order to break out of the loop.
In the average function, I renamed the list variable to "mylist" so as to not confuse anyone who might analyze the code as list is a word that has significance in Python.
Finally, the return of the average was added to the end of the function. If a return statement is not included in a function, a value of "None" will be returned by a function, which is most likely why you received the error.
Following was a test run from the terminal.
#Dev:~/Python_Programs/Average$ python3 Average.py
Enter a number: 10
Enter a number: 22
Enter a number: 40
Enter a number: -1
24.0
Give that a try and see if it meets the spirit of your project.
converts the resulting list to Type: None
No, it doesn't. You get a ValueError with int() when it cannot parse what is passed.
You can try-except that. And you can just use while True.
Also, your average function doesn't output anything, but if it did, you need to call it with a parameter, not only print the function object...
ex.
from statistics import fmean
def average(data):
return fmean(data)
number_list = []
while True:
x = input('Enter a number')
try:
val = int(x)
if val == -1:
break
number_list.append(val)
except:
break
print(average(number_list))
edit
my program calculates the average to be 2 not 3
Your calculation includes the -1 appended to the list , so you are running 8 / 4 == 2
You don't need to save all the numbers themselves, just save the sum and count.
You should check if the input is a number before trying to convert it to int
total_sum = 0
count = 0
while True:
number = input("Enter a number: ")
if number == '-1':
break
elif not number.isnumeric() and not (number[0] == "-" and number[1:].isnumeric()):
print("Please enter numbers only")
continue
total_sum += int(number)
count += 1
print(total_sum / count)
I have the next exercise:
Write a program that repeatedly prompts a user for integer numbers until the user enters 'done'. Once 'done' is entered, print out the largest and smallest of the numbers. If the user enters anything other than a valid number catch it with a try/except and put out an appropriate message and ignore the number. Enter 7, 2, bob, 10, and 4 and match the output below.
And this is the code i have developed so far but i still can't get it to work properly. I accept any corrections needed. Thank you.
largest = None
smallest = None
while True:
value = input('Enter a Number: ')
if smallest is None:
smallest = value
elif smallest < value:
smallest = value
if largest is None:
largest = value
elif largest > value:
largest = value
if value == 'done':
break
try:
fvalue = float(value)
except:
print('Invalid input')
continue
print(f'Maximun is', max(largest))
print(f'Minimun is', min(smallest))
Your code has several problems and some of those have been addressed in the comments.
The first thing your code should do is to check, if "done" was entered so that we can break the loop. Then you should try to convert the number to an integer (you used float) and display an error message if there was a ValueError. You have to convert the value before you do the comparison because otherwise the comparison will be lexicographically. Then you have to change the comparisons. You want to set a new number to smallest if smallest is bigger than the current value, not the other way round. And the last thing: Using max and min on a single value doesn't make sense.
This gives us:
largest = None
smallest = None
while True:
value = input('Enter a Number: ')
if value == 'done':
break
try:
value = int(value)
except ValueError:
print('Invalid input')
continue
if smallest is None or smallest > value:
smallest = value
if largest is None or largest < value:
largest = value
print(f'Maximum is', largest)
print(f'Minimum is', smallest)
I think you went in a wrong way when you've chosen to use a contraction like that with if/else
for that task it's better to use something like this
a = set()
while (inp := input('Enter a Number: ')) != 'done':
try:
if str(inp).isnumeric() != True:
raise
a.add(inp)
except Exception as ex:
print(f'your "{inp}" is not appropriate')
print(f'max == {max(a)}', f', min == {min(a)}')
set() stores unique values only
it's easy to get max an min from set() by built-in functions max() and min()
so we just need not to allow to our set anything but numbers - here it's done by while loop and try/except inside it
it's easy to read and to change cuz it's without redundancy
I am trying to learn Python through a course on Courser, and so far having a feeling I am not going to be able to.
I don't want an answer to the assignment, I want someone to push me in the right direction. Because Im stuck and the online tutors there are not being any help just repeating the obvious that is already stated in the assignment. The assignment is very simple, but I cant understand what I am missing.
Here is the assignment:
Write a program that repeatedly prompts a user for integer numbers until the user enters 'done'. Once 'done' is entered, print out the largest and smallest of the numbers. If the user enters anything other than a valid number catch it with a try/except and put out an appropriate message and ignore the number. Enter the numbers from the book for problem 5.1 and Match the desired output as shown.
Here is my code, i tried using the example codes we where show for getting the minimum and maximum, but the problem is in the examples we had they had lists, here I was told I dont need a list. But everytime the value of num changes with ever new input, how can i get the program to choose from certain numbers if they are not storing...or do you think i can enter lists in the raw_input?
while True:
inpt = raw_input("Enter a number: ")
if inpt == "done" : break
try:
num = int(inpt)
except:
print "Invalid input"
continue
largest = None
if largest is None:
largest = num
elif num > largest:
largest = num
smallest = None
if smallest is None:
smallest = num
elif num < smallest:
smallest = num
print "Maximum is", largest
print "Minimum is", smallest
The numbers from the book are 4, 5, 7 and a word
Thank you everyone for your support, I understand what I have to do, not sure if I understand how I will get there, but Im going to sit and keep trying. Meanwhile I am getting issues with indentation
let's say I rewrote the code like this and want to add an if statement into the while loop
largest = None
smallest = None
while True:
inpt = raw_input("Enter a number: ")
if inpt == "done" : break
try:
num = int(inpt)
except:
print "Invalid input"
continue
should the if statement start with the same indent as the continue and then the inside of the if indented again?? Because Im getting errors when I do that
largest = None
smallest = None
while True:
inp = input("Enter a number: ")
if inp == "done" : break
try:
num = float(inp)
except:
print ("Invalid input")
continue
if smallest is None:
smallest=num
if num > largest :
largest=num
elif num < smallest :
smallest=num
def done(largest,smallest):
print("Maximum is", int(largest))
print("Minimum is", int(smallest))
done(largest,smallest)
this will surly work.
You're on the right track with your current implementation, but there is some issues in the order of your operations, and where the operations are taking place. Trace through your program step by step, and try to see why your None assignment may be causing some issues, among other small things.
You are being asked to keep a running max and running min, the same way you could keep a running total. You just update the running <whatever> inside the loop, then discard the user's most recent input. In the case of running total, the code would look like tot = tot + newinput and you could then discard newinput (or, more likely, reuse it) without recording it in a list or any other data structure.
Not every problem permits a "running" solution. For instance, if you wanted to give the user an undo feature, letting them back out some of the numbers they entered earlier, you would have to keep an exact history of all the numbers. But here, you can get by without keeping that data.
You should check for the largest and smallest numbers inside the loop. First check if its a number - if yes, carry on and see if it is bigger than your current largest variable value (start with 0). If yes, replace it. See, if its smaller than your smallest value (start with the first number that comes in, if you start with 0 or just a random number, you might not get lower that that. If you start with the first number, then it'll definitely be the smallest (after all the loops)), etc, etc. All of that should be done inside the loop and after the loop should be just the printing. And yes, you don't need to use lists.
Let me give you a hint here, every time your while loop takes in a input, it sets the values of largest and smallest to None. Where should you initialize them?
I sense that your confusion partly stems from how the user is expected to give the input. One could interpret the instructions in two ways.
The user writes 4 5 7 randomword [ENTER]
The user writes 4 [ENTER] 5 [ENTER] 7 [ENTER] randomword [ENTER]
If it was the first variant, then you might be expected to process the whole thing as a list and determine its parts
However, the fact that they told you "you will not need lists for this exercise" implies that they expect the second scenario. Which means you should design your while loop such that at each iteration it expects to receive a single input from the user, and do something with it (i.e. check if it's bigger / smaller than the last). Whereas the loop you have now, will simply always keep the last input entered, until "done" is encountered.
Once you're out of the while loop, all you need to do is present the variables that you've so carefully collected and kept updating inside the loop, and that's it.
I figured it out I think, and the thing that was killing my code was the continue statement if I am not wrong
here is what i got, and please leave comments if I got it wrong
largest = None
smallest = None
while True:
inpt = raw_input("Enter a number: ")
if inpt == "done" : break
try:
num = int(inpt)
except:
print "Invalid input"
if largest is None:
largest = num
elif num > largest:
largest = num
if smallest is None:
smallest = num
elif num < smallest:
smallest = num
print "Maximum is", largest
print "Minimum is", smallest
largest = None
smallest = None
while True:
inp = input("Enter a number: ")
if inp == "done" : break
try:
num = float(inp)
except:
print ("Invalid input")
continue
if smallest is None:
smallest=num
if num > largest :
largest=num
elif num < smallest :
smallest=num
def done(largest,smallest):
print("Maximum is", int(largest))
print("Minimum is", int(smallest))
done(largest,smallest)
maximum = -1
minimum = None
while True:
num = input('Enter the num: ')
if num == 'done':
break
try:
num1 = int(num)
except:
print('Invalid input')
continue
if minimum is None:
minimum = num1
if num1 > maximum:
maximum = num1
elif num1 < minimum:
minimum = num1
print('Maximum is', maximum)
print('Minimum is', minimum)
largest = None
smallest = None
while True:
num = input("Enter a number: ")
if num == "done" :
break
try:
n=int(num)
except:
print("Invalid input")
continue
if largest is None:
largest=n
if n > largest:
largest=n
if smallest is None:
smallest=n
elif n < smallest:
smallest =n
print("Maximum is", largest)
print("Minimum is" , smallest)
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smallest = None
largest = None
while True :
number = raw_input('Enter a number from -10 to 9: ')
if largest < number :
largest = number
if smallest is None :
smallest = number
elif number < smallest :
smallest = number
if number == 'done': break
print 'Largest number is: ',largest
print 'Smallest number is ',smallest
I have no idea why my "smallest" is alright while "largest" outcome is always done. I think that "break" is somehow affecting it. Could You point out my mistake?
The problem is that you are first updating smallest and largest even if the user entered done. So first of all, you should check whether the input is 'done' and abort immediately before updating any of your numbers.
That being said, there are multiple other issues with your code:
if largest < number – You are updating largest if the number is smaller than the previously stored one, making it have the same logic as smallest. Of course, you will not end up with the largest number that way.
raw_input() returns a string, not a number. So if the user types for example 5, then what raw_input() returns is the string '5'. So every comparison you make is a string comparison (e.g. '2' < '5'). Because string comparisons are based on character codes, this will incidentally work for single-digit numbers but you should really convert the strings into proper numbers first.
You mention an allowed range of -10 to 9 but you never actually enforce that.
Something like this will work:
smallest = None
largest = None
while True:
number = raw_input('Enter a number from -10 to 9: ')
if number == 'done':
break
# convert into a number
try:
num = int(number)
except ValueError:
print('That was not a valid number')
continue # restart the loop
# validate the number range
if num < -10 or num > 9:
print('The number is out of the allowed range')
continue
if largest is None or num > largest:
largest = num
if smallest is None or num < smallest:
smallest = num
print 'Largest number is:', largest
print 'Smallest number is:', smallest
If you encounter done, your loop should break immediately. But in your codes, you have put the break at the end. So before that, previous logic is being executed. And done as a string can be compared.
>>> None < 'done'
True
>>>
So your largest is set to done since largest < None in that case.
Quick Fix
We now moved the break on top, so this should fix the issue:
smallest = None
largest = None
while True :
number = raw_input('Enter a number from -10 to 9: ')
if number == 'done':
break
if largest < number :
largest = number
if smallest is None :
smallest = number
elif number < smallest :
smallest = number
print 'Largest number is: ',largest
print 'Smallest number is ',smallest
Handling Numbers
The raw_input returns string. But we want to compare numbers. So we should convert the inputs to int.
try:
num = int(number)
except ValueError:
print('Please enter a valid integer')
continue # skip the input and continue with the loop
I try to use python to prompt user to enter different number, and keep the largest one, and finish when user enter "done". but I find out it can not work with different digit of number. for example, 1st entry: 91, 2nd:94, it will run well. but 1st entry:91 and 2nd:100, it can not record 100 as the largest number. did somebody know what's going on? thank you so much!
code:
largest = None
smallest = None
while True:
num = raw_input("Enter a number: ")
if num == "done":
break
try: int (num)
except:
print "Please enter a numeric number"
if largest is None and smallest is None:
largest = num
smallest = num
#print "l", largest
#print "s", smallest
if num > largest:
largest = num
print largest, num
#if num < smallest:
# smallest = num
# print "s2", smallest
print num
print "Maximum is ", largest
#print "Minimum is ", smallest
you're doing ASCII comparisons, not numeric. you need to actually assign something like number = int(num) and use number for comparison.
The problem is you're not converting num to an integer, so it's using string comparison rather than numeric comparison. Change:
try: int (num)
to:
try:
num = int(num)
You've got a number of problems. Take a look at this, maybe you can incorporate it into your own code?
largest = 0
while True:
prompt = raw_input("Enter a number: ")
try:
num = int(prompt)
if num > largest:
largest = num
except:
if prompt == 'done':
break
print largest
raw_input returns a string. So when you compare num > largest you are using string (alphabetical) comparison. You want to compare numbers. The easiest way would be to simply rewrite the comparion to int(num) > int(largest).
try: int (num) ... already checks if the input is a number but it does not change the value of the variable.
Note: except without an exception type is generally not a good idea. You should explicitly write down the exception you want to catch: ValueError