snippetpythonTip

Map dictionary values

Submitted by: @import:30-seconds-of-code·Mar 2, 2026·

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mappythondictionaryvalues

Problem

Have you ever wanted to create a dictionary with the same keys as the provided dictionary and values generated by running the provided function for each value? Luckily, there's a quick and easy way to do this in Python.
Using dict.items(), you can iterate over the dictionary. Then, you can assign the values produced by the function to each key of a new dictionary. And that's it!

Solution

def map_values(obj, fn):
  return dict((k, fn(v)) for k, v in obj.items())

users = {
  'fred': { 'user': 'fred', 'age': 40 },
  'pebbles': { 'user': 'pebbles', 'age': 1 }
}
map_values(users, lambda u : u['age']) # {'fred': 40, 'pebbles': 1}

Code Snippets

def map_values(obj, fn):
  return dict((k, fn(v)) for k, v in obj.items())

users = {
  'fred': { 'user': 'fred', 'age': 40 },
  'pebbles': { 'user': 'pebbles', 'age': 1 }
}
map_values(users, lambda u : u['age']) # {'fred': 40, 'pebbles': 1}

Context

From 30-seconds-of-code: map-values

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