Python | Dictionary | List of Dictionaries

Introduction

In Python, a dictionary is a collection of key-value pairs. Sometimes, we need to extract specific values from a list of dictionaries. In this challenge, you need to write a function that takes a list of dictionaries and a key as input and returns a list of values corresponding to the specified key.

Skills Graph

%%%%{init: {'theme':'neutral'}}%%%% flowchart RL python(("Python")) -.-> python/BasicConceptsGroup(["Basic Concepts"]) python(("Python")) -.-> python/ControlFlowGroup(["Control Flow"]) python(("Python")) -.-> python/DataStructuresGroup(["Data Structures"]) python(("Python")) -.-> python/FunctionsGroup(["Functions"]) python/BasicConceptsGroup -.-> python/comments("Comments") python/ControlFlowGroup -.-> python/for_loops("For Loops") python/ControlFlowGroup -.-> python/list_comprehensions("List Comprehensions") python/DataStructuresGroup -.-> python/lists("Lists") python/DataStructuresGroup -.-> python/tuples("Tuples") python/DataStructuresGroup -.-> python/dictionaries("Dictionaries") python/FunctionsGroup -.-> python/function_definition("Function Definition") subgraph Lab Skills python/comments -.-> lab-13705{{"Pluck values from list of dictionaries"}} python/for_loops -.-> lab-13705{{"Pluck values from list of dictionaries"}} python/list_comprehensions -.-> lab-13705{{"Pluck values from list of dictionaries"}} python/lists -.-> lab-13705{{"Pluck values from list of dictionaries"}} python/tuples -.-> lab-13705{{"Pluck values from list of dictionaries"}} python/dictionaries -.-> lab-13705{{"Pluck values from list of dictionaries"}} python/function_definition -.-> lab-13705{{"Pluck values from list of dictionaries"}} end

Pluck values from list of dictionaries

Write a function pluck(lst, key) that takes a list of dictionaries lst and a key key as arguments and returns a list of values corresponding to the specified key.

You need to:

Use a list comprehension and dict.get() to get the value of key for each dictionary in lst.
The function should return an empty list if the input list is empty or if the specified key is not present in any of the dictionaries.

def pluck(lst, key):
  return [x.get(key) for x in lst]

simpsons = [
  { 'name': 'lisa', 'age': 8 },
  { 'name': 'homer', 'age': 36 },
  { 'name': 'marge', 'age': 34 },
  { 'name': 'bart', 'age': 10 }
]
pluck(simpsons, 'age') ## [8, 36, 34, 10]

Summary

In this challenge, you learned how to extract specific values from a list of dictionaries using a list comprehension and dict.get(). You also learned how to handle empty input lists and non-existent keys.