Examples of how to sum a list of numbers in python:
Using the sum() function
To add all the elements of a list, a solution is to use the built-in function sum(), illustration:
>>> list = [1,2,3,4]
>>> sum(list)
10
Example with float numbers:
>>> l = [3.1,2.5,6.8]
>>> sum(l)
12.399999999999999
Note: it is possible to round the sum (see also Floating Point Arithmetic: Issues and Limitations):
>>> round(sum(l),1)
12.4
Iterate through the list:
Example using a for loop:
>>> list = [1,2,3,4]
>>> tot = 0
>>> for i in list:
... tot = tot + i
...
>>> tot
10
Sum a list including different types of elements
Another example with a list containing: integers, floats and strings:
>>> l = ['a',1,'f',3.2,4]
>>> sum([i for i in l if isinstance(i, int) or isinstance(i, float)])
8.2
Merge a list of "strings":
Note: in the case of a list of strings the function sum() does not work:
>>> list = ['a','b','c','d']
>>> sum(list)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for +: 'int' and 'str'
use the function join() instead:
>>> ','.join(list)
'a,b,c,d'
>>> ' '.join(list)
'a b c d'
References
Links | Site |
---|---|
Built-in Functions | |
Summing elements in a list | stackoverflow |
string — Common string operations | python doc |
Joining elements of a list - Python | stackoverflow |