Python Dictionary

How to Return Dictionary Keys as a List in Python?

Short answer: use the expression list(dict.keys()). Problem Formulation Given a dictionary that maps keys to values. Return the keys as a list. For example: Given dictionary {‘Alice’: 18, ‘Bob’, 21, ‘Carl’: 24} Return the keys as a list [‘Alice’, ‘Bob’, ‘Carl’] Solution The dict.keys() method returns a list of all keys in Python 2. The …

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Python – How to Check if a Dict Key Exists?

Summary: To check whether a key exists in a dictionary, you can use: The in keyword The keys() method The get() method The has_key() method Overview Mastering dictionaries is one of the things that differentiates the expert coders from the intermediate coders. Why? Because dictionaries in Python have many excellent properties in terms of runtime—and …

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Python Dictionary Get Value – A Simple Illustrated Guide

Whether you are a beginner or a professional, dictionaries are an integral part of your programming journey, especially if you are coding in Python. Python dictionaries are all about key-value pairs which help you to perform your task. There are restrictions on dictionary keys, but values have none. Literally, anything can be a value. As …

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How to Switch Keys and Values in a Python Dictionary?

Problem: Given a dictionary in Python; how to switch Keys and Values?  Method 1: Using a for loop   Method 2: Using the zip function Method 3: Using the map and reverse functions Method 4: Using a dictionary comprehension Summary: Use one of the following methods to switch between the keys and values in a dictionary with unique values. …

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How to Create a Dictionary From Two NumPy Arrays?

Anyone working with lists of data will encounter a need to combine them in a useful way. Often the best result is a dictionary consisting of keys and values. In this article, you’ll learn how to create a dictionary from two NumPy arrays. Problem Formulation: Given two NumPy arrays a and b. Create a dictionary …

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How to Find the Maximum Value in a Python Dict?

There are three problem variants of finding the maximum value in a Python dictionary: Find the maximum value and return this maximum value Find the maximum value and return a (key, value) tuple of both the key and the max value itself Find the maximum value and return only the key assigned to the max …

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How to Sort a Dictionary in Python By Key?

To sort a dictionary by key in Python, use the dictionary comprehension expression {key:dict[key] for key in sorted(dict)} to create a new dictionary with keys in sorted order. You iterate over all keys in sorted order, obtain their associated values with rank[key], and put them into a new dictionary. Python dictionaries preserve the order—even if …

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Dictionaries and Unpacking Arguments in Python

Programming is about using lower-level functionality to create higher-level functionality. In general, any programming language is a collection of functions that in turn build upon functions provided by the operating system. You must master the art of building your own code with the help of existing functionality, instead of reinventing the wheel! Keyword Arguments Functions …

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