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I have a list that looks like this:

['9,7,4', '10,5,6,5,5', '10,8,5,3,0', '8,4,2']

How can i convert the numbers to ints and add the individual string values together?

So the desired out put would be

['20','31','26','14']

Use map to convert the splitted (using , as the delimiter) string values into int followed by a list comprehension to get the sum

input_list = ['9,7,4', '10,5,6,5,5', '10,8,5,3,0', '8,4,2']
output = [str(sum(map(int, x.split(',')))) for x in input_list]
print (output)

Output

['20', '31', '26', '14']

I edited after seeing your desired output as strings

Python, Given a list of numbers, write a Python program to find the sum of all the elements in the list. Example: Input: [12, 15, 3, 10] Output: 40 Input: [17, 5, 3, 5] Output:  It is the simplest approach in Python to add two list elements. In this method, a for loop is used to iterate the smaller of the two lists. In every iteration, add the corresponding values at the running index from the two lists, and insert the sum in a new list.

[sum(map(int, group.split(','))) for group in l]

Python program to find sum of elements in list, Assuming both lists a and b have same length, you do not need zip, numpy or anything else. Python 2.x and 3.x: [a[i]+b  In this method, we simply run a loop and append to the new list the summation of the both list elements at similar index till we reach end of the smaller list. This is the basic method to achieve this task. # Python code to demonstrate. # addition of two list. # initializing lists. test_list1 = [1, 3, 4, 6, 8] test_list2 = [4, 5, 6, 2, 10]

Someone mentioned eval, so I think you should take this a step further with a safe-eval alternative:

>>> import ast
>>> [ast.literal_eval(v.replace(',', '+')) for v in lst]
>>> [20, 31, 26, 14]

One thing I like about this answer is that it is purely a non-functional approach (no map inside a list comprehension, which is fine but I don't really believe in mixing paradigms).

Obviously this will only work if you have numbers separated by a single comma, without any leading or trailing characters and invalid arithmetic expressions.

I leave the conversion to string as an exercise.

Add SUM of values of two LISTS into new LIST, Hello everyone, am back to discuss about a new python program. Here we learn how to sum Duration: 2:13 Posted: Oct 3, 2016 In this python program, we are using For Loop to iterate each element in a given List. Inside the loop, we are adding elements of the first and second lists. # Python Program to Add two Lists NumList1 = [10, 20, 30] NumList2 = [15, 25, 35] total = [] for j in range(3): total.append( NumList1[j] + NumList2[j]) print(" The total Sum of Two Lists = ", total) OUTPUT

If all strings are in this format you can try to use eval function - this will convert numbers into tuples from which you can count sum.

>>> l = ['9,7,4', '10,5,6,5,5', '10,8,5,3,0', '8,4,2']
>>> sums = [sum(numbers) for numbers in map(eval, l)]
>>> sums
[20, 31, 26, 14]

If you want output list to contain strings these values can be easily mapped:

[str(value) for value in sums]
# or
map(str, sums)

Python program to calculate the sum of elements in a list, Python has a great built-in list type named "list". The '+' works to append two lists, so [1, 2] + [3, 4] yields [1, 2, 3, 4] (this is print sum ## 30. Five Ways to Add Data to a List in Python. Append, insert, extend, and more The most common change made to a list is adding to its elements. method will append the supplied-list values to

Python Lists | Python Education, The sum() function calculates the sum of the numbers of the n list. $ ./​sequence_funs.py There are 8 items Maximum is 8 Minimum is 1 The sum of  # Define a list heterogenousElements = [3, True, 'Michael', 2.0] The list contains an int, a bool, a string, and a float. Access Values in a List. Each item in a list has an assigned index value. It is important to note that python is a zero indexed based language. All this means is that the first item in the list is at index 0.

Python lists - working with lists in Python, Welcome back to another edition of the How to Python series. This time I want to sum elements of two lists in Python. I got… In short, one of the best ways to sum elements of two lists in Python is to use a list comprehension in conjunction with the addition operator. For example, we could perform an element-wise sum of two lists as follows: [x + y for x, y in zip (list_a, list_b)]. But, as always, we’ll take a look at other options. Table of Contents.

How to Sum Elements of Two Lists in Python: Comprehensions and , Python add two list elements using zip() and sum() # Setting up lists in_list1 = [11, 21,  Python Program to Add Two Numbers. In this program, you will learn to add two numbers and display it using print() function. To understand this example, you should have the knowledge of following Python programming topics: In the program below, we've used the arithmetic addition operator (+) to add two numbers.

Comments
  • loop through the list, split the strings by commas, convert to ints (int(string)) and sum the resultant list.
  • You should do this, if I understood: 1) iterate through the strings, 2) split the strings on commas 3) convert split strings to integers, 4) merge the result into one list. Which part do you have a question about?
  • So, the true question is: how to find the sum of '9,7,4'? (If you can do that, you can do the rest.) split the string, convert each fragment to an int, apply sum, convert back to a string.
  • Hey, i updated my question. Sorry for the confusion.
  • @JamesHomes: If the answers below were helpful in solving your problem, you should accept the answer you find the best.
  • using map inside a list comprehension is quite expensive. I guess you ould use vectorized functions after splitting.
  • [str(sum(np.array(i.split(","),dtype="i"))) for i in input_list]