How to ask for 20 numbers in python and, then, print the sum of positives and quantities of negatives?

Question

The problem seems very simple but I'm cracking my head over it. It's just an algorithm exercise. This is what I have so far:

positivesum = 0

negativeqt = 0

value = int(input(("Enter the numbers: ")))

for _ in range(20):

  value

  if value > 0:

    positivesum = positivesum + value

    print("The sum of positives is ", positivesum)`

Also, if someone could translate the same exercise in Javascript, I would appreciate it.

Answer 1

Something like this?
Python:

sum_positive_number = 0
negative_number_quantities = 0

numbers = 20
for i in range(numbers):
    number_input = int(input(f'Enter number #{i+1}: '))
    if number_input > 0:
        sum_positive_number += number_input
    elif number_input < 0:
        negative_number_quantities += 1

print('Sum of positive numbers: ', sum_positive_number)
print('Quantities of negative numbers: ', negative_number_quantities)

Answer 2

int_list = [int(inp) for inp in input("Enter 20 numbers: ").split()]
pos_sum = sum(num for num in int_list if num > 0)
neg_quantity = len([num for num in int_list if num < 0])

print(f"{pos_sum=} {neg_quantity=}")

How It Works

int_list is something called a list comprehension. When prompted with the input, a user is able to input the 20 numbers, with spaces in between the different numbers due to the call to split(). split() by default will split by a white space character. split() will return an iterable list, so we iterate over that list with for inp in …. int(inp) will convert each of the numbers from type str to type int. input() returns a string, so this is needed to do number operations

pos_sum calls the sum built in and passes it a generator expression. It iterates over the list resulting from all of the operations done in int_list and only looks for the numbers that are greater than 0. It will add these up, giving us our sum.

neg_quantity calls the len built in and passes in an iterable list to len, constructed through a list comprehension. The resulting list from the comprehension will contain all numbers from int_list less than 0, and len will return the length of that list, giving us our quantity of negatives

Answer 3

nums = list(map(int, input('Enter the numbers: ').split()))
pos = sum(num for num in nums if num > 0)
neg = len(num for num in nums if num < 0)
print(pos, neg)

split the input separated by whitespace by default and map each substring, i.e. number, to its int. list initializes a list to store the result of of map.

Notice that sum takes iterable. Expressions in the form of num for num in nums if num > 0 are generators. A generator yields a result one by one according to the condition until it terminates. When a generator expression is passed into a function as an argument, the result is passed as a tuple which is iterable. Therefore pos gives you the sum of all positive numbers in the list. Compared to a list comprehension, generators do not demand extra space and once the result is passed in, python can automatically collect the garbage for you.

This answer explains a little bit more about generator expressions and provides another way to get and store the input.

sum(iterable,/,start=0)

len(s)

map(function,iterable,...)

Answer 4

Your issue is that you put the input statement in the wrong place:

positivesum = 0
negativeqt = 0

for _ in range(20):
    value = int(input(("Enter the numbers: ")))
    if value > 0:
       positivesum += value
    else if value < 0:
       negativeqt += 1

If you only ask for one input then the user can only give you one number. Since you want twenty numbers, you need to put the input inside your for-loop so you get a value every time you need a value.

With regard to the difference between calculating positivesum and negativeqt, you're looking for the total of the positive terms so you need to add them together whereas you only want the quantity of negative terms so we increment once every time we see one.

Answer 5

positive = 0
negative = 0
for i in range(-10 , 10):
    print(i)



    if i >= 0:
        positive += i
    elif i <= 0:
        negative += 1
print(positive)
print(negative)

Answer 6

As your own example states, Tag.create works but Tags.findAll doesn't. Have you tried Tag.findAll()? I use init for defining models but IIRC you should match the variable name to the table name.