I am trying to add all of the negative integers in a user input list, but the function always returns 0 as the answer. It works if I include the list as part of the function, but not when its user input. The code I have is:
def sumNegativeInts[userList]:
userList = []
sum = 0
for i in userList:
if i < 0:
sum = sum + i
return sum
userList = input["Enter a list of +/- integers: "]
print[sumNegativeInts[userList]]
thefourtheye
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asked Nov 2, 2015 at 2:50
1
sum[i for i in alist if i < 0]
Done. It's Python, it has to be simple!
answered Nov 2, 2015 at 3:09
Dima TisnekDima Tisnek
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remove the second line of your code, it sets the input to an empty list no matter what your input is.
answered Nov 2, 2015 at 3:41
You assign an empty list to userList every time you enter the function, how can it not be 0?
Further more, the function input[] seems not able to handle a list of inputs.
So I think you can do this:
def sumNegativeInts[userList]:
sum = 0
for i in userList:
if i < 0:
sum += i
return sum
inputData = raw_input['some prompts']
userList = [int[i] for i in inputData.split[' ']]
print[sumNegativeInts[userList]]
answered Nov 2, 2015 at 3:03
sunhssunhs
3911 silver badge6 bronze badges
You could always just do if and elif statements to determine whether or not to add a number to a list and then take the sum of the list. My prompt is making a list of 100 number with random integers from -100 to 100. Then finding the sum of all the negative numbers.
import random
def SumNegative[]:
my_list = []
for i in range[100]:
x = random.randint[-100, 100]
if x > 0:
pass
elif x < 0:
my_list.append[x]
print[sum[my_list]]
SumNegative[]
answered May 15, 2019 at 22:20
1
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Given a list. The task is to find the sum of Negative, Positive Even, and Positive Odd numbers present in the List.
Examples:
Input: -7 5 60 -34 1 Output: Sum of negative numbers is -41 Sum of even positive numbers is 60 Sum of odd positive numbers is 6 Input: 1 -1 50 -2 0 -3 Output: Sum of negative numbers is -6 Sum of even positive numbers is 50 Sum of odd positive numbers is 1
Negative numbers are the numbers less than 0 while positive even numbers are numbers greater than 0 and also divisible by 2. 0 is assumed to be a positive even number, in this case.
Approach:
- The first approach input a list of numbers from the user.
- Two loops are run, one for the positive numbers and the other for the negative numbers, computing the numbers’ summation.
- If n is the size of the list of numbers,
- it takes O[2n] time complexity, for iterating over the list of numbers twice.
Python3
class Sumofnumbers:
def negSum[self, list]:
neg_sum = 0
for num in list:
num = int[num]
if[num < 0]:
neg_sum + = num
print["Sum of negative numbers is ", neg_sum]
def posSum[self, list]:
pos_even_sum = 0
pos_odd_sum = 0
for num in list:
num = int[num]
if[num >= 0]:
if[num % 2 == 0]:
pos_even_sum + = num
else:
pos_odd_sum +
= num
print["Sum of even positive numbers is ",
pos_even_sum]
print["Sum of odd positive numbers is ",
pos_odd_sum]
list_num = [-7, 5, 60, -34, 1]
obj = Sumofnumbers[]
obj.negSum[list_num]
obj.posSum[list_num]
Output:
Sum of negative numbers is -41 Sum of even positive numbers is 60 Sum of odd positive numbers is 6
The second approach computes the sum of respective numbers in a single loop. It maintains three counters for each of the three conditions, checks the condition and accordingly adds the value of the number in the current sum . If n is the size of the list of numbers, it takes O[n] time complexity, for iterating over the list of numbers once.
Python3
class Sumofnumbers:
def Sum[self, list]:
neg_sum = 0
pos_even_sum =
0
pos_odd_sum = 0
for num in list:
num = int[num]
if[num < 0]:
neg_sum += num
else:
if[num % 2 == 0]:
pos_even_sum + = num
else:
pos_odd_sum + = num
print["Sum of negative numbers is ",
neg_sum]
print["Sum of even positive numbers is ",
pos_even_sum]
print["Sum of odd positive numbers is ",
pos_odd_sum]
list_num = [1, -1, 50, -2, 0, -3]
obj = Sumofnumbers[]
obj.Sum[list_num]
Output:
Sum of negative numbers is -6 Sum of even positive numbers is 50 Sum of odd positive numbers is 1
Method: Using list comprehension
Python3
lst = [1, -1, 50, -2, 0, -3];i=0
x=[i for i in lst if i>0 and i%2==0]
y=[i for i in lst if i>0 and
i%2!=0]
z=[i for i in lst if i0 and i%2==0],lst]]
y=list[filter[lambda i: [i>0 and i%2!=0],lst]]
z=list[filter[lambda
i: [i0]
y=[int[i] for a,i in enumerate[lst] if int[i]%2!=0 and int[i]>0]
z=[int[i] for a,i in enumerate[lst] if
int[i] operator, known as greater than or lesser than the operator.