## Summing elements in a list

### Question

Here is my code, I need to sum an undefined number of elements in the list. How to do this?

```
l = raw_input()
l = l.split(' ')
l.pop(0)
```

My input: `3 5 4 9`

After input I delete first element via `l.pop(0)`

.
After `.split(' ')`

my list is `['5', '4', '9']`

and I need to sum all elements in this list.

In this case the sum is 18. Please notice that number of elements is not defined.

### Accepted Answer

You can sum numbers in a list simply with the sum() built-in:

```
sum(your_list)
```

It will sum as many number items as you have. Example:

```
my_list = range(10, 17)
my_list
[10, 11, 12, 13, 14, 15, 16]
sum(my_list)
91
```

**For your specific case**:

For your data convert the numbers into `int`

first and then sum the numbers:

```
data = ['5', '4', '9']
sum(int(i) for i in data)
18
```

This will work for **undefined** number of elements in your list (as long as they are "numbers")

Thanks for @senderle's comment re conversion in case the data is in string format.

Read more... Read less...

```
>>> l = raw_input()
1 2 3 4 5 6 7 8 9 10
>>> l = l.split()
>>> l.pop(0)
'1'
>>> sum(map(int, l)) #or simply sum(int(x) for x in l) , you've to convert the elements to integer first, before applying sum()
54
```

Python iterable can be summed like so - `[sum(range(10)[1:])]`

. This sums all elements from the list except the first element.

```
>>> atuple = (1,2,3,4,5)
>>> sum(atuple)
15
>>> alist = [1,2,3,4,5]
>>> sum(alist)
15
```

You can also use reduce method:

```
>>> myList = [3, 5, 4, 9]
>>> myTotal = reduce(lambda x,y: x+y, myList)
>>> myTotal
21
```

Furthermore, you can modify the lambda function to do other operations on your list.

You can use `sum`

to sum the elements of a list, however if your list is coming from `raw_input`

, you probably want to convert the items to `int`

or `float`

first:

```
l = raw_input().split(' ')
sum(map(int, l))
```

You can use `map`

function and pythons inbuilt `sum()`

function. It simplifies the solution. And reduces the complexity.

`a=map(int,raw_input().split())`

`sum(a)`

Done!