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 … Read more
[toc] Introduction A Python dictionary stores data in the form of key-value pairs. A dictionary in Python is ordered, mutable and does not allow duplicates. The keys in the dictionary are paired with the values by using a colon (:) while the commas fill in as a separator for the pairs. The values can be the same but … Read more
Introduction Before diving into the solutions to our question, here’s a quick recap of Python dictionaries. In Python, a dictionary is a collection of objects. A Python dictionary stores data in the form of key-value pairs. A dictionary in Python is ordered, changeable and does not allow duplicates. The keys in the dictionary are paired … Read more
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 … Read more
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 … Read more
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. … Read more
Summary: To iterate over the dictionary items in random order get the list of items in a tuple with .items() or get the list of keys with .keys() or extract the values in a list using .values() , then shuffle and iterate through this list using the shuffle() method of the random module. Problem: Given a … Read more
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 … Read more
There are three problem variants of finding the maximum value in a Python dictionary: In the following, you’ll learn how to solve those in the most Pythonic way: Find Maximum Value & Return Only Value The output is: Find Maximum Value & Return (Key, Value) Pair The output is: Find Maximum Value & Return Only … Read more
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 … Read more
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 … Read more
If used without argument, Python’s built-in dir() function returns the function and variable names defined in the local scope—the namespace of your current module. If used with an object argument, dir(object) returns a list of attribute and method names defined in the object’s scope. Thus, dir() returns all names in a given scope. Usage Learn … Read more