Python | Maximum List Value Based on Function

Introduction

In Python, we can use the max() function to find the maximum value in a list. However, what if we want to find the maximum value after mapping each element to a value using a provided function? In this challenge, you will need to write a function that takes a list and a function as arguments, maps each element to a value using the provided function, and returns the maximum value.

Skills Graph

%%%%{init: {'theme':'neutral'}}%%%% flowchart RL python(("Python")) -.-> python/BasicConceptsGroup(["Basic Concepts"]) python(("Python")) -.-> python/DataStructuresGroup(["Data Structures"]) python(("Python")) -.-> python/FunctionsGroup(["Functions"]) python/BasicConceptsGroup -.-> python/comments("Comments") python/DataStructuresGroup -.-> python/lists("Lists") python/DataStructuresGroup -.-> python/tuples("Tuples") python/DataStructuresGroup -.-> python/dictionaries("Dictionaries") python/FunctionsGroup -.-> python/function_definition("Function Definition") python/FunctionsGroup -.-> python/lambda_functions("Lambda Functions") python/FunctionsGroup -.-> python/build_in_functions("Build-in Functions") subgraph Lab Skills python/comments -.-> lab-13686{{"Find Maximum List Value Based on Function"}} python/lists -.-> lab-13686{{"Find Maximum List Value Based on Function"}} python/tuples -.-> lab-13686{{"Find Maximum List Value Based on Function"}} python/dictionaries -.-> lab-13686{{"Find Maximum List Value Based on Function"}} python/function_definition -.-> lab-13686{{"Find Maximum List Value Based on Function"}} python/lambda_functions -.-> lab-13686{{"Find Maximum List Value Based on Function"}} python/build_in_functions -.-> lab-13686{{"Find Maximum List Value Based on Function"}} end

Find Maximum List Value Based on Function

Write a function max_by(lst, fn) that takes a list lst and a function fn as arguments. The function should map each element in lst to a value using the provided function fn, and then return the maximum value.

def max_by(lst, fn): return max(map(fn, lst))

max_by([{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }], lambda v : v['n']) ## 8

Summary

In this challenge, you have learned how to find the maximum value in a list after mapping each element to a value using a provided function. You have written a function max_by(lst, fn) that takes a list and a function as arguments, maps each element to a value using the provided function, and returns the maximum value.