Python | Combine two lists by maintaining duplicates in first list

Given two lists, the task is to combine two lists and removing duplicates, without removing duplicates in original list.

Example:

Input : 
list_1 = [11, 22, 22, 15]
list_2 = [22, 15, 77, 9]

Output :
OutList = [11, 22, 22, 15, 77, 9]

Code #1: using extend

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python code to combine two lists
# and removing duplicates, without
# removing duplicates in original list.
  
# Initialisation of first list
list1 = [111, 222, 222, 115]
  
# Initialisation of Second list
list2 = [222, 115, 77, 19]
  
output = list(list1)
  
# Using extend function
output.extend(y for y in list2 if y not in output)
  
# printing result
print(output)

chevron_right


Output:



[111, 222, 222, 115, 77, 19]

 
Code #2 : Using Set and Iteration
Append those element in first list which are not in second list and then take union of first and second list.

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python code to combine two lists 
# and removing duplicates, without 
# removing duplicates in original list.
  
# Initialisation of first list
list1 = [11, 22, 22, 15]
  
# Initialisation of Second list
list2 = [22, 15, 77, 9]
  
# creating set
unique_list1 = set(list1)
unique_list2 = set(list2)
  
# Difference in two sets
diff_element = unique_list2 - unique_list1
  
# union of difference + first list
output = list1 + list(diff_element)
  
# printing output
print(output) 

chevron_right


Output:

[11, 22, 22, 15, 9, 77]

Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.

To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course.




My Personal Notes arrow_drop_up


If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.