How to make a single list from multiple lists in Python
In this article we will learn how to make a single list from multiple lists in Python, that is, to condense several lists into one in a simple way.
Hey you all programmers, how are you? Let’s learn more about lists in Python!
To achieve this goal we have some possibilities, in the first one we want to show you, we will make a loop with another loop inside, and we will use the” for” statement
The first loop goes through all the lists, the second loop goes through each item in the lists and adds to the main list which will be our only
Let’s see an example:
a = [1,2,3,4] b = [5,6,7,8] c = [9,10] listWithLists = [a,b,c] myList =  for l in listWithLists : for i in l: myList.append(i) print(listaUnica)
This way the loop runs through lists a, b and c, and the loop inside each list appends the item to the singlelist
Another possibility is to use the itertools library
We will have the same result, but in fewer lines of code
See an example:
import itertools a = [1,2,3,4] b = [5,6,7,8] c = [9,10] listWithLists = [a,b,c] myList = list(itertools.chain(*listWithLists)) print(myList)
The output of both options will be:
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
Another interesting way, however should be avoided in production because of the performance
It’s using Monoids, basically it adds the lists passed to the second argument which will be an empty list
See the example:
a = [1,2,3,4] b = [5,6,7,8] c = [9,10] listWithLists = [a,b,c] myList = sum(listWithLists, ) print(myList)
In addition to the performance issue, this statement is very implicit.
That is, it does not follow the standards of Pythonic code, so it should be avoided and only learned out of curiosity!
you will see other points that the assert addresses
In this article we learned how to make a single list from multiple lists
We use several approaches such as: for and for, itertools and a monoid