Compute sum of digits of a given string in python

The best (Pythonic) way to do it using list comprehension and sum(). Try this:

sumAndAverage = "English = 78 Science = 83 Math = 68 History = 65"

li = [int(x) for x in sumAndAverage if x.isdigit()]
print("List:", li, "=", sum(li))

Output:

List: [7, 8, 8, 3, 6, 8, 6, 5] = 51

If you want to calculate the sum of numbers in your string:

sumAndAverage = "English = 78 Science = 83 Math = 68 History = 65"

li = [int(x) for x in sumAndAverage.split() if x.isdigit()]
print("List:", li, "=", sum(li))

Output:

List: [78, 83, 68, 65] = 294

Try using re:

sumAndAverage = "English = 78 Science = 83 Math = 68 History = 65"
nums = re.findall('\d+', sumAndAverage)
nums = [int(num) for num in nums]
print(sum(nums))
# 294

Regex will try and find all numbers in your string, store them to a list, then you just need to sum them up.

Here you have a possible solution. Now you have as a result 229 (78 + 83 + 65).

The problem with your code was that you were summing all the numbers in the string, but you did not consider that number may be more than one character in length.

sumAndAverage = "English = 78 Science = 83 Math = 68 History = 65"

def sum_digits_string(str1):
    sum_digit = 0
    num = ""
    for x in str1:
        if x.isdigit():
            num += x
        else:
            if num != "":
                z = int(num)
                sum_digit += z
                num = ""
    return sum_digit 

print(sum_digits_string(sumAndAverage))

It's because you're casting each digit separately, so what you're doing is 7 + 8 + 8 + 3 + 6 + 8 + 6 + 5 which is indeed 51. What you want to do here is splitting your string and casting the entire numbers, try something like this :

sumAndAverage = "English = 78 Science = 83 Math = 68 History = 65"

def sum_digits_string(str1):
    sum_digit = 0

    for x in str1.split(" "):
        if x.isdigit():
            z = int(x)
            sum_digit = sum_digit + z

    return sum_digit 

print(sum_digits_string(sumAndAverage))

That is working an giving 294.

str = 'English = 78 Science = 83 Math = 68 History = 65'    
a = sum([int(s) for s in str.split() if s.isdigit()])
print(a)

Your current code is printing sum of individual digits and not numbers. In your case, you can use split() method to achieve what you intend to do:

sumAndAverage = "English = 78 Science = 83 Math = 68 History = 65"

def sum_digits_string(str1):
    sum_digit = 0

    for x in str1.split():
        if x.isdigit():
            sum_digit += int(x)

    return sum_digit

print(sum_digits_string(sumAndAverage))

Output: 294

You can also achieve this with a single line of code

sumAndAverage = "English = 78 Science = 83 Math = 68 History = 65"

Solution 1:

from functools import reduce

>>> reduce(lambda a, x: int(a)+int(x), [int(s) for s in sumAndAverage.split() if s.isdigit()])
294

Solution 2:

>>> sum([int(s) for s in sumAndAverage.split() if s.isdigit()])
294