Get Sum of a List in Python

  1. Sum a List in Python With the sum() Function
  2. Get Sum of a List by Iteration Over List

The list is one of the most commonly used data structures in Python. In other programming languages, they are regarded as arrays, and they have the same functionality.

Sum a List in Python With the sum() Function

The most basic and simplistic way to sum a list in Python is to use Python’s in-built function sum().

myList = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
listSum = sum(myList)
print(f"Sum of list -> {listSum}")

Output:

Sum of list -> 55

The sum() function accepts two arguments. The first argument is an iterable data structure, and the second argument is the start index. An iterable data structure could be a list of numbers, Python dictionaries, and tuples. And the start index is basically the position in the iterable data structure from where the summing process should start.

If a list of anything other than numeric values is directly provided to the sum() method, it will raise a TypeError.

In such cases, you’ve to filter the data, or other words, preprocess the data.

For example, if you have a list of numeric strings, you must first convert strings to their numeric equivalents and then sum them. Refer to the following code for the same.

myList = ["1", "3", "5", "7", "9"]
myNewList = [int(string) for string in myList]
sum1 = sum(myNewList)
sum2 = sum(number for number in myNewList)
print(f"Sum of list -> {sum1}")
print(f"Sum of list -> {sum2}")

Output:

Sum of list -> 25
Sum of list -> 25

Get Sum of a List by Iteration Over List

myList = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
listSum = 0

for number in myList:
    listSum += number

print(f"Sum of list -> {listSum}")

Output:

Sum of list -> 55

The above code iterates over each element of the list, adds them to a variable, and finally prints the sum.

If you want to follow a more conventional way of iterating over the indexes and accessing elements using them, refer to the following code snippet.

myList = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
length = len(myList)
listSum = 0

for i in range(length):
    listSum += myList[i]

print(f"Sum of list -> {listSum}")

Output:

Sum of list -> 55
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