Python List Examples – How to Concatenate Two or more Lists in Python

In this post we will see how to merge two or more lists in python – various list examples.

Method 1 -Concatenate Two or more Lists in Python

Lets take example of two list as follow –

List1 = [1,2,3,4,5]

List2 = [6,7,8,9]

Output after merging two list should be –

 

CombinedList = [ 1,2,3,4,5,6,7,8,9]

I python this can be done very easily by simply joining them using ‘+’ operator as –

CombineList =List1 + List 2

a,b=[1,2,3],[4,5] 
c=a+b 
c

Lets Try to Run it –

Method 2 – Concatenate Two List using Extend

Lets take another route  to achieve same task – Using Extend  – here is example –

a = [‘it’]
b = [‘is’]
c = [‘nice’]

a.extend(b)
a.extend(c)

We should have output as –

a = [‘it’, is’, ‘nice’]

 

Lets try to run this program –

 

Method 3- Use Itertools to Concatenate List

There are multiple ways to merge lists in python, in this method we will use itertools to merge the two list as follows –

import itertools
list = itertools.chain(['it'], ['is'], ['nice']) 
list(list)
list

Lets try to execute it –

 

Bonus Method – Most Commonly Used

Lets take an live example where your lists are dynamic i.e. you dont know the  number of lists and you want to merge all the list then you need to use the extend method in loop to merge all the lists.

Example :

a=[['one','two'],['three','four']]
outList=[]
for i in a:
    outList.append(i)

 

Try to find output of this program, take this as the exercise.