Add only Numeric Values Present in a List - Python

To sum only the numeric values in a list containing mixed data types, we iterate through the list, filter out non-numeric elements and then calculate the sum of the remaining numeric values.

Using filter and sum

One efficient to handle this is by combining the filter() function with the sum() function. filter() function selects only the numeric elements such as integers or floats based on a specified condition and the sum() function then calculates the total of these filtered values.

li = [1, 2, 3, 4, 'a', 'b', 'x', 5, 'z']
# sum to add only numeric values
res = sum(filter(lambda x: isinstance(x, int), li))
print(res)

15

Explanation:

• filter(lambda x: isinstance(x, int), li): This applies a condition to each element of the list li .
• lambda x: isinstance(x, int): This part checks whether each element x is of type int.
• filter(): This returns a filtered iterator containing only the elements that satisfy the condition i.e. the integers from the list [1, 2, 3, 4, 5].
• sum() :This takes the filtered iterator and calculates the sum of the elements. In this case, it adds the integers 1 + 2 + 3 + 4 + 5, resulting in 15.

Using list comprehension

list comprehension is a powerful way to create new lists by applying an expression to each element in an existing list. When combined with the sum() function, it provides an efficient method for filtering and summing only the numeric values from a list that contains mixed data types.

li = [1, 2, 3, 4, 'a', 'b', 'x', 5, 'z']
res = sum([x for x in li if isinstance(x, int)])
print(res)

15

Explanation:

• list comprehension : This filters the list li to include only integer values and the condition isinstance(x, int) checks if each element x is an integer.
• sum() : This function then adds the values in the filtered list .

Using for loop

for loop is a simple way to iterate through a list and sum numeric values. While easy to understand, it is less efficient than methods like filter() and list comprehension as it requires manually checking each element and summing conditionally.

li = [1, 2, 3, 4, 'a', 'b', 'x', 5, 'z']

# Manually summing numeric values using a loop
res = 0
for item in li:
    if isinstance(item, int):
        res += item

print(res)

15

Explanation:

• For Loop: This iterates through each item in the list li.
• isinstance(item, int): This checks if the current item is an integer.
• res += item: This adds the integer values to res in each iteration.