Hướng dẫn add two lists python
Join Two ListsThere are several ways to join, or concatenate, two or more lists in Python. Show
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One of the easiest ways are by using the ExampleJoin two list: list1 = ["a", "b" , "c"] list3 = list1 + list2 Try it Yourself » Another way to join two lists are by appending all the items from list2 into list1, one by one: ExampleAppend list2 into list1: list1 = ["a", "b" , "c"] for x in list2: print(list1) Try it Yourself » Or you can use the ExampleUse the list1 = ["a", "b" , "c"] list1.extend(list2) Try it Yourself » All the possible ways to join lists that I could find
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In this article we will discuss different ways to Merge / Join two or more lists in python. Table of Contents
Suppose we have two lists i.e. # List of strings list1 = ["This" , "is", "a", "sample", "program"] # List of ints list2 = [10, 2, 45, 3, 5, 7, 8, 10] We want to merge the contents of these two list into a single list i.e. ['This', 'is', 'a', 'sample', 'program', 10, 2, 45, 3, 5, 7, 8, 10] There are different ways to do this. Let’s discuss them by one by one. Advertisements Join / Merge two lists in python using + operatorIn python, we can use the + operator to merge the contents of two lists into a new list. For example, We can use + operator to merge two lists i.e. # List of strings list_1 = ["This" , "is", "a", "sample", "program"] # List of ints list_2 = [10, 2, 45, 3, 5, 7, 8, 10] # Merge two lists final_list = list_1 + list_2 print('Merged List:') print(final_list) Output: Merged List: ['This', 'is', 'a', 'sample', 'program', 10, 2, 45, 3, 5, 7, 8, 10] It returned a new concatenated lists, which contains the contents of both list_1 and list_2. Whereas, list_1 and list_2 remained same as original. Join / Merge two lists in python using list.extend()In the previous example, we created a new list containing the contents of the both the lists. But what if we want to extend any existing list? We can extend any existing list by concatenating the contents of any other lists to it using the extend() function of list i.e. list.extend(anotherList) list.extend() makes a list longer by appending the elements of another list at the end of the calling list object. For example, # List of strings list_1 = ["This" , "is", "a", "sample", "program"] # List of ints list_2 = [10, 2, 45, 3, 5, 7, 8, 10] # Makes list1 longer by appending the elements of list2 at the end. list_1.extend(list_2) print('Merged List:') print(list_1) Output Merged List: ['This', 'is', 'a', 'sample', 'program', 10, 2, 45, 3, 5, 7, 8, 10] It extended the list_1 by adding the contents of list_2 at the end of list_1. Join / Merge two lists in python using unpackingIn python, we can unpack the contents on any iterable object using the * operator. So, *list will unpack the contents of a list. We can unpack the contents of both the lists and create a new list with the merged contents. For example, # List of strings list_1 = ["This" , "is", "a", "sample", "program"] # List of ints list_2 = [10, 2, 45, 3, 5, 7, 8, 10] # Merge two lists final_list = [*list_1, *list_2] print('Merged List:') print(final_list) Output: Merged List: ['This', 'is', 'a', 'sample', 'program', 10, 2, 45, 3, 5, 7, 8, 10] It unpacked the contents of both the lists and created a new list with the contents of both the lists. In python, the itertools module provides a function chain() to merge the contents of multiple iterable sequences, itertools.chain(*iterables) It creates a chain of all the iterable sequences passed as arguments and returns an iterator. This iterator returns the elements from first iterable sequence until it is exhausted and then moves to the next iterable. We can use this iterator to created a merged list of contents. For example, import itertools # List of strings list_1 = ["This" , "is", "a", "sample", "program"] # List of ints list_2 = [10, 2, 45, 3, 5, 7, 8, 10] # Join two lists final_list=list(itertools.chain(list_1, list_2)) print('Merged List:') print(final_list) Output: Merged List: ['This', 'is', 'a', 'sample', 'program', 10, 2, 45, 3, 5, 7, 8, 10] Join / Merge two lists in python using for loopWe can iterate over all elements of a list using for loop and during iteration we can append each element to an another list. This way we can extend the contents of a list. For example, # List of strings list_1 = ["This" , "is", "a", "sample", "program"] # List of ints list_2 = [10, 2, 45, 3, 5, 7, 8, 10] # Iterate over a list and add elements to another list for elem in list_2: list_1.append(elem) print('Extended List:') print(list_1) Output: Extended List: ['This', 'is', 'a', 'sample', 'program', 10, 2, 45, 3, 5, 7, 8, 10] We iterated over all the elements in list_2 and while iteration added each element at the end of list_1. Therefore list_1 is now extended and contains the contents of both the lists i.e. original list_1 and list_2. Join / Merge multiple lists using + operatorWe can merge the contents of multiple lists to a new list using the + operator. For example, list_1 = ["This" , "is", "a", "sample", "program"] list_2 = [10, 2, 45, 3, 5, 7, 8, 10] list_3 = [11, 12, 13] # Merge 3 lists into a single list merged_list = list_1 + list_2 + list_3 print('Merged List:') print(merged_list) Output: Merged List: ['This', 'is', 'a', 'sample', 'program', 10, 2, 45, 3, 5, 7, 8, 10, 11, 12, 13] Conclusion: We learned about different ways to join or merge multiple lists in python. Can we add 2 lists in Python?There are several ways to join, or concatenate, two or more lists in Python. One of the easiest ways are by using the + operator. Can you add lists to lists in Python?There are four methods to add elements to a List in Python. append() : append the element to the end of the list. insert() : inserts the element before the given index. extend() : extends the list by appending elements from the iterable. |