when I run this code it adds to the list so I can't find the median. How would I make it so empty values do not get added to the list

import statistics
import time
amount=int(input('How many marks are you going to 
input? (most 10) '))
while amount>10:
    print('No')
    time.sleep(1)
else:
    print(amount)
    input_string=input('Enter marks of students 
separated by a space:   ')
    print('\n')
    user_list = input_string.split()
    print('list: ', user_list)
    user_list=map(int, user_list)
    print('Mean = ', sum(user_list)/amount)
    sorted_string=sorted(input_string)
    print(sorted_string)
    new=(amount 1)//2
    print(new)
    median=sorted_string[new]
    print(median)

CodePudding user response：

First issue

You are iterating through a map more than once, which leaves you with a bug of sorting an empty collecting. (I suggest you read more about it: map() returns an iterator)

to demonstrate the issue:

my_map = map(int, ['1', '2', '3'])

print('first run')
for i in my_map:
    print(i)

print('second run')
for i in my_map:
    print(i)

output:

first run
1
2
3
second run

Second issue

You are passing input_string to sorted() instead of user_list which is what I assume you want?

Example

Fixing (1) and (2) will result in the expected output:

import statistics
import time
amount=int(input('How many marks are you going to input? (most 10) '))
while amount>10:
    print('No')
    time.sleep(1)
else:
    print(amount)
    input_string=input('Enter marks of students separated by a space:   ')
    print('\n')
    user_list = input_string.split(' ')
    print('list: ', user_list)
    user_list=list(map(int, user_list))
    print('Mean = ', sum(user_list)/amount)
    sorted_string=sorted(user_list)
    print(sorted_string)
    new=(amount 1)//2
    print(new)
    median=sorted_string[new]
    print(median)`

dialogue:

How many marks are you going to input? (most 10) 2
2
Enter marks of students separated by a space:   100 95


list:  ['100', '95']
Mean =  97.5
[95, 100]
1
100

Side notes

Outside the context of your question, consider:

1. Taking the amount from the given list, instead of requesting for an amount explicitly
2. If the amount given is >10, then there is an infinite loop saying 'No'. Just making sure this is intentional.

CodePudding user response：

I think you meant to sort user_list and not input_string as currently it sorts the input string char by char:

How many marks are you going to input? (most 10) 3
> 3
Enter marks of students separated by a space:   90 100 90
> list:  ['90', '100', '90']

sorted_string=sorted(input_string)
[' ', ' ', '0', '0', '0', '0', '1', '9', '9']

Sort user_list:

sorted_string=sorted(user_list)

list: ['90', '90', '100']

Will sort the input grades.

This should work for you:

import statistics
import time

amount=int(input('How many marks are you going to input? (most 10) '))
while int(amount)>10:
    print('No')
    time.sleep(1)
else:
    print(amount)
    input_string=input('Enter marks of students separated by a space:   ')
    print('\n')
    user_list = [int(x) for x in input_string.split()]
    print('list: ', user_list)
    #user_list=map(int, user_list)
    print(user_list)
    print('Mean = ', sum(user_list)/amount)
    sorted_string=sorted(user_list)
    print(sorted_string)
    new=int((amount)//2)
    print(new)
    median = sorted_string[new]
    print(median)

I commented the map method to keep user_list as list, and converted each input to integer in advance.

Also, new variable logic was wrong (amount 1), and was changed to amount//2. Notice that it only works when the list length is odd.

To handle even lists:

new=int((amount)//2)
if len(sorted_string) % 2 == 0: # even length
    # do average of new and new-1
    median = (sorted_string[new]   sorted_string[new-1]) / 2
else: # odd length
    median = sorted_string[new]