Sort the values of first list using second list in Python Last Updated : 24 Dec, 2024 Comments Improve Suggest changes Like Article Like Report Sorting the values of the first list using the second list in Python is commonly needed in applications involving data alignment or dependency sorting. In this article, we will explore different methods to Sort the values of the first list using the second list in Python.Using zip() and sorted() zip() function pairs elements from two lists and sorted() allows us to sort these pairs based on the second list. Python a = ['a', 'b', 'c', 'd'] b = [3, 1, 4, 2] # Sort a using b x = [val for _, val in sorted(zip(b, a))] print(x) Output['b', 'd', 'a', 'c'] Explanation:zip(b, a) pairs the elements of the second list (b) with the first list (a).sorted() sorts these pairs based on the first element (from list b).A list comprehension extracts the sorted elements from list a.Let's see some more methods and see how we can sort the values of one list using another list in PythonTable of ContentUsing numpy.argsort()Using a Custom Sorting Function with sort()Using pandasUsing numpy.argsort()If working with numerical lists, numpy.argsort() provides a fast way to obtain indices for sorting. Python import numpy as np a = ['a', 'b', 'c', 'd'] b = [3, 1, 4, 2] # Sort list_a using numpy.argsort() sorted_a = [a[i] for i in np.argsort(b)] print(sorted_a) Output['b', 'd', 'a', 'c'] Explanation:np.argsort(b) =returns indices that would sort b.These indices are used to rearrange elements of list a.Using a Custom Sorting Function with sort()For a more manual approach, we can use a custom sorting function with sorted(). This method involves sorting list by using a custom sorting function. Python a = ['with', 'GFG', 'Learn', 'Python'] b = [3, 4, 1, 2] # Using sort() with a custom sorting function list1_sorted = sorted(a, key=lambda x: b[a.index(x)]) print(list1_sorted) Output['Learn', 'Python', 'with', 'GFG'] Explanation:The sorted() function is used with a custom key function.The key is determined by finding the index of each element in 'a' and mapping it to the corresponding value in 'b'.Using PandasFor tabular data or scenarios involving data frames, pandas provides a convenient way to sort one column based on another. Python import pandas as pd a = ['a', 'b', 'c', 'd'] b = [3, 1, 4, 2] # Create a DataFrame df = pd.DataFrame({'a': a, 'b': b}) # Sort by column 'b' and extract 'a' sorted_a = df.sort_values('b')['a'].tolist() print(sorted_a) Output:['b', 'd', 'a', 'c']Explanation:A data frame is created with a and b as columns.The sort_values() method sorts based on column b.The sorted a column is converted back to a list. Comment More infoAdvertise with us Next Article Sort the values of first list using second list in Python saketkumr Follow Improve Article Tags : Sorting Python Python Programs DSA python-list Python list-programs +2 More Practice Tags : pythonpython-listSorting Similar Reads Python Lists In Python, a list is a built-in dynamic sized array (automatically grows and shrinks). We can store all types of items (including another list) in a list. A list may contain mixed type of items, this is possible because a list mainly stores references at contiguous locations and actual items maybe s 6 min read Get a list as input from user in Python We often encounter a situation when we need to take a number/string as input from the user. In this article, we will see how to take a list as input from the user using Python.Get list as input Using split() MethodThe input() function can be combined with split() to accept multiple elements in a sin 3 min read Create List of Numbers with Given Range - Python The task of creating a list of numbers within a given range involves generating a sequence of integers that starts from a specified starting point and ends just before a given endpoint. For example, if the range is from 0 to 10, the resulting list would contain the numbers 0, 1, 2, 3, 4, 5, 6, 7, 8 3 min read Python - Add List Items Python lists are dynamic, which means we can add items to them anytime. In this guide, we'll look at some common ways to add single or multiple items to a list using built-in methods and operators with simple examples:Add a Single Item Using append()append() method adds one item to the end of the li 3 min read How to add Elements to a List in Python In Python, lists are dynamic which means that they allow further adding elements unlike many other languages. In this article, we are going to explore different methods to add elements in a list. For example, let's add an element in the list using append() method:Pythona = [1, 2, 3] a.append(4) prin 2 min read Python List AccessPython - Access List ItemWhether we are working with numbers, strings or other data types, lists provide a versatile way to organize and manipulate data. But how to access specific items in a list? This article will guide you through various methods of accessing list items in Python.Accessing List Items by IndexIn Python, l 3 min read Accessing index and value in Python listWe are given a list, and our task is to access both the index and value of each element in the list using Python. For example, using enumerate(list) in a loop like for index, value in enumerate(list) allows us to access both the index and the value together.Using enumerate() enumerate() is preferred 2 min read Accessing all elements at given list of indexes-PythonSometimes, you may have a list of data and a separate list of indexes and the goal is to extract only the elements at those specific positions. For example, given a list [10, 20, 30, 40, 50] and a list of indexes [1, 3, 4], you want to retrieve [20, 40, 50] the values at those index positions in the 2 min read Python List SlicingPython list slicing is fundamental concept that let us easily access specific elements in a list. In this article, weâll learn the syntax and how to use both positive and negative indexing for slicing with examples.Example: Get the items from a list starting at position 1 and ending at position 4 (e 4 min read List Iteration OperationsIterate over a list in PythonPython provides several ways to iterate over list. The simplest and the most common way to iterate over a list is to use a for loop. This method allows us to access each element in the list directly.Example: Print all elements in the list one by one using for loop.Pythona = [1, 3, 5, 7, 9] # On each 3 min read How to iterate through a nested List in Python?A nested list is a list that contains other lists. Working with nested lists can seem tricky at first but it becomes easy once we understand how to iterate through them. This is the easiest way to loop through a nested list. We can use a for loop to access each sublist in the main list, and then use 3 min read Python | Iterate over multiple lists simultaneouslyIterating over single lists, refers to using for loops for iteration over a single element of a single list at a particular step whereas in iterating over multiple lists simultaneously, we refer using for loops for iteration over a single element of multiple lists at a particular step. Iterate over 4 min read Iterate Over a List of Lists in PythonWe are given a list that contains multiple sublists, and our task is to iterate over each of these sublists and access their elements. For example, if we have a list like this: [[1, 2], [3, 4], [5, 6]], then we need to loop through each sublist and access elements like 1, 2, 3, and so on. Using Nest 2 min read Python List Search OperationsHow To Find the Length of a List in PythonThe length of a list refers to the number of elements in the list. There are several methods to determine the length of a list in Python. For example, consider a list l = [1, 2, 3, 4, 5], length of this list is 5 as it contains 5 elements in it. Let's explore different methods to find the length of 2 min read Python | Find elements of a list by indicesGiven two lists with elements and indices, write a Python program to find elements of list 1 at indices present in list 2. Examples: Input : lst1 = [10, 20, 30, 40, 50] lst2 = [0, 2, 4] Output : [10, 30, 50] Explanation: Output elements at indices 0, 2 and 4 i.e 10, 30 and 50 respectively. Input : l 5 min read Python program to find String in a ListSearching for a string in a list is a common operation in Python. Whether we're dealing with small lists or large datasets, knowing how to efficiently search for strings can save both time and effort. In this article, weâll explore several methods to find a string in a list, starting from the most e 3 min read Python - Ways to find indices of value in listIn Python, it is common to locate the index of a particular value in a list. The built-in index() method can find the first occurrence of a value. However, there are scenarios where multiple occurrences of the value exist and we need to retrieve all the indices. Python offers various methods to achi 3 min read Python | Find most frequent element in a listGiven a list, find the most frequent element in it. If multiple elements appear a maximum number of times, print any one of them using Python.ExampleMake a set of the list so that the duplicate elements are deleted. Then find the highest count of occurrences of each element in the set and thus, we f 2 min read Python List Remove OperationsPython - Remove List ItemRemoving List Item can be achieved using several built-in methods that provide flexibility in how you remove list items. In this article, we'll explore the different ways to remove list items in Python.Removing Item by Value with remove()The remove() method allows us to remove the first occurrence o 3 min read How to Remove Item from a List in PythonLists in Python have various built-in methods to remove items such as remove, pop, del and clear methods. Removing elements from a list can be done in various ways depending on whether we want to remove based on the value of the element or index.The simplest way to remove an element from a list by i 3 min read Python | Remove given element from the listGiven a list, write a Python program to remove the given element (list may have duplicates) from the given list. There are multiple ways we can do this task in Python. Let's see some of the Pythonic ways to do this task. Example: Input: [1, 8, 4, 9, 2] Output: [1, 8, 4, 2] Explanation: The Element 9 7 min read Ways to remove particular List element in PythonThere are times when we need to remove specific elements from a list, whether itâs filtering out unwanted data, deleting items by their value or index or cleaning up lists based on conditions. In this article, weâll explore different methods to remove elements from a list.Using List ComprehensionLis 2 min read Remove Multiple Elements from List in PythonIn this article, we will explore various methods to remove multiple elements from a list in Python. The simplest way to do this is by using a loop. A simple for loop can also be used to remove multiple elements from a list.Pythona = [10, 20, 30, 40, 50, 60, 70] # Elements to remove remove = [20, 40, 2 min read Python List Concatenation OperationsPython - Concatenate two lists element-wiseIn Python, concatenating two lists element-wise means merging their elements in pairs. This is useful when we need to combine data from two lists into one just like joining first names and last names to create full names. zip() function is one of the most efficient ways to combine two lists element- 3 min read Merge Two Lists in PythonPython provides several approaches to merge two lists. In this article, we will explore different methods to merge lists with their use cases. The simplest way to merge two lists is by using the + operator. Let's take an example to merge two lists using + operator.Pythona = [1, 2, 3] b = [4, 5, 6] # 4 min read Concatenate two list of lists Row-wise-PythonThe task of concatenate two lists of lists row-wise, meaning we merge corresponding sublists into a single sublist. For example, given a = [[4, 3], [1, 2]] and b = [[7, 5], [9, 6]], we pair elements at the same index: [4, 3] from a is combined with [7, 5] from b, resulting in [4, 3, 7, 5], and [1, 2 3 min read Python program to concatenate every elements across listsGiven 2 lists, perform concatenations of all strings with each other across list. Input : test_list1 = ["gfg", "is", "best"], test_list2 = ["love", "CS"] Output : ['gfg love', 'gfg CS', 'is love', 'is CS', 'best love', 'best CS'] Explanation : All strings are coupled with one another. Input : test_l 4 min read Concatenate all Elements of a List into a String - PythonWe are given a list of words and our task is to concatenate all the elements into a single string with spaces in between. For example, given the list: li = ['hello', 'geek', 'have', 'a', 'geeky', 'day'] after concatenation, the result will be: "hello geek have a geeky day".Using str.join()str.join() 2 min read Concatenate All Records - PythonThe task of concatenating all records in Python involves combining elements from a list, typically strings, into a single unified string. The goal is to concatenate each individual element, ensuring that the result is a continuous string without spaces or delimiters, unless specified. For example, g 3 min read Python - Merge list elementsMerging list elements is a common task in Python. Each method has its own strengths and the choice of method depends on the complexity of the task. This is the simplest and most straightforward method to merge elements. We can slice the list and use string concatenation to combine elements.Pythona = 2 min read Python | Concatenate N consecutive elements in String listSometimes, while working with data, we can have a problem in which we need to perform the concatenation of N consecutive Strings in a list of Strings. This can have many applications across domains. Let's discuss certain ways in which this task can be performed. Method #1: Using format() + zip() + i 8 min read Python | Merge two lists alternativelyGiven two lists, write a Python program to merge the given lists in an alternative fashion, provided that the two lists are of equal length. Examples: Input : lst1 = [1, 2, 3] lst2 = ['a', 'b', 'c'] Output : [1, 'a', 2, 'b', 3, 'c'] Input : lst1 = ['name', 'alice', 'bob'] lst2 = ['marks', 87, 56] Ou 4 min read Python - Union of two or more ListsThe union of two or more lists combines all elements ensuring no duplicates if specified. In this article we will explore various methods to get a union of two lists.Using set.union (Most Efficient for Uniqueness)The union() method ensures that the resulting list contains unique elements. Here we co 2 min read Like