Python program to find the sum of number digits in list

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Method 1: Using loop and finding digit Sum for each

To find the digit sum, we will use a recursive call to a function that returns the sum of digits of a number for the given number.

We will loop for all elements of the array and for each element will we call the function to find the digit sum.

Algorithm:

1. Loop over the array and perform steps 2-4 for each value.
2. Take the number, if it is 0, return zero
3. If the number is not zero, go to step 2, with
   number = number / 10
4. Return the value extracted from step 3 and add the last digit of the initial number.
5. Print all values.

Program to find the sum of number digits in the list

# Python program to find sum of number digits

# Method to find the sum of number digits 
def sumDigits(num):
  if num == 0:
    return 0
  else:
    return num % 10 + sumDigits(int(num / 10))
    
# Getting list from user
myList = []
length = int(input("Enter number of elements : "))
for i in range(0, length):
    value = int(input())
    myList.append(value)

digitSumList = []
for ele in myList:
    digitSum = sumDigits(ele)
    digitSumList.append(digitSum)
    
# Printing values 
print("Entered List : ", myList)
print("Digit Sum List : ", digitSumList)

Output:

Enter number of elements : 5
12345
54321
123
567
89012
Entered List :  [12345, 54321, 123, 567, 89012]
Digit Sum List :  [15, 15, 6, 18, 20]

Method 2: Using str() method

An alternate method could be loop on the list and convert each element to a string and then perform addition for each digit of the element which will give the digitSum.

Algorithm:

• Loop over the list
  • Convert each element to a string and loop over the string.
    • Add all the digits of the list.
    • store the sum value of sumList.
• Print the sumList.

Program to find the sum of number digits in the list using str() method

# Python program to find sum of number digits

# Getting list from user
myList = []
length = int(input("Enter number of elements : "))
for i in range(0, length):
    value = int(input())
    myList.append(value)

digitSumList = []
for ele in myList:
    digitSum = 0
    for singleDigit in str(ele):
        digitSum += int(singleDigit)
    digitSumList.append(digitSum)
    
# Printing values 
print("Entered List : ", myList)
print("Digit Sum List : ", digitSumList)

Output:

Enter number of elements : 5
12345
54321
123
456
890123
Entered List :  [12345, 54321, 123, 456, 890123]
Digit Sum List :  [15, 15, 6, 15, 23]

Method 3: Using list comprehension

Python's built-in comprehension feature that lets us reduce the number of lines in list creation to a single line.

We can use the list comprehension in place of loops. And for performing the sum we will use the built-in sum() function.

Program to find the sum of number digits in the list

# Python program to find sum of number digits

# Getting list from user
myList = []
length = int(input("Enter number of elements : "))
for i in range(0, length):
    value = int(input())
    myList.append(value)

# finding the sum of number digits
digitSumList = list(map(lambda ele: sum(int(sub) for sub in str(ele)), myList))
    
# Printing values 
print("Entered List : ", myList)
print("Digit Sum List : ", digitSumList)

Output:

Enter number of elements : 5
12345
54321
123
456
890156
Entered List :  [12345, 54321, 123, 456, 890156]
Digit Sum List :  [15, 15, 6, 15, 29]

The list comprehension performs the same task as we have done in another method, which is for each element of the list we have converted to a string and found the sum of digits using the sum() method.

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