Combine two lists in Python

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In this tutorial, we will see how to combine twolist in python

There are multiple ways to combine list in python.


Using + operator

You can use + operator to combine list in python.

Let’s understand with the help of example.

list1=[1,2,3,4] list2=[5,6,7,8] combinedList = list1 + list2 print("Combined List:",combinedList)

Output:

Combined List: [1, 2, 3, 4, 5, 6, 7, 8]

As you can see combined list has joined list1 and list2


Using itertools.chain

Let’s understand with the help of example.

import itertools list1=[10,20,30,40] list2=[50,60,70,80] for i in itertools.chain(list1,list2): print(i)

Output:

10
20
30
40
50
60
70
80

There are two advantages of using this approach.

  • You don’t have to create copy of list to iterate over elements
  • You can combine other iterables such as set and tuple as well

Using Additional Unpacking Generalizations

There is another way to combine two lists in python>=3.5 version.Additional Unpacking Generalizations reduces synthetic sugar with * operator but it may not be very easy to understand. This approach is bit faster than other two.

list1=[10,20,30,40] list2=[50,60,70,80] combinedList=[*list1,*list2] print("Combind list:",combinedList)

Output:

Combind list: [10, 20, 30, 40, 50, 60, 70, 80]

Remove duplicates in combined list

In case you want to remove duplicates in combined list, you can use + operator and then convert it to set and back to list.

list1=[10,20,30,40] list2=[50,10,20,60] combinedList=list(set(list1 + list2)) print("Combind list without duplicates:",combinedList)

Output:

Combind list without duplicates: [40, 10, 50, 20, 60, 30]

That’s all about how to combine two lists in python

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