Summary: The dictionary data structure has many useful methods, one of these methods is the dict.items() method. To be able to iterate and show the dictionary elements, the Python dictionary items() method does this functionality. The dict.items() method shows the elements taken up by a dictionary as a list of key-value tuples. Definition: The dict.items() … Read more
The method dict.fromkeys() is a very useful method for creating new dictionaries from a given iterable of keys. Definition: dict.fromkeys() is a method that inputs keys and maybe an optional value, and outputs a dictionary with the specified keys, that are mapped either to optionally specified values or to the default None value. dict.fromkeys() Syntax … Read more
In this blog post, you’ll learn about the Python Dictionary clear() method. But, before I cover the clear() method I would like to give a brief definition of what a Python Dictionary is. Definition: A Python dictionary data structure is a collection of key-value pairs that are unordered, and are accessed by a key instead … Read more
A Python nested dictionary is a dictionary with another dictionary or dictionaries nested within (dictionary of dictionaries or collection of collections). Nested dictionaries are one way to represent structured data (similar to a database table(s) relationship). An analogy for this concept is the Russian Nesting Dolls. Our article focuses on various ways to retrieve … Read more
The Python dictionary is a structure used to store data. This data type is appropriate when the data needs to contain labels (unique keys) associated with a value (key:value). Python lists are not able to handle this format. The list(s) will require conversion to a dictionary format (key:value). There are various ways to accomplish this … Read more
Python defines the dictionary data type as an unordered collection that contains key:value pairs. The key:value pairs (separated by commas) are wrapped inside curly braces ({}). Each key inside the dictionary must be unique and immutable. Dictionary keys can be one of the following data types: integer, string, or tuple. Dictionary keys can not … Read more
Problem Formulation Given a string representation of a dictionary. How to convert it to a dictionary? Input: ‘{“1”: “hi”, “2”: “alice”, “3”: “python”}’ Output: {‘a’: 1, ‘b’: 2, ‘c’: 3} Method 1: eval() The built-in eval() function takes a string argument, parses it as if it was a code expression, and evaluates the expression. If … Read more
Problem Formulation Given a Unicode string representation of a dictionary. How to convert it to a dictionary? Input: u”{‘a’: 1, ‘b’: 2, ‘c’: 3}” Output: {‘a’: 1, ‘b’: 2, ‘c’: 3} Note: The u’string’ representation represents a Unicode string that was introduced in Python 3. This is redundant as all strings in Python 3 are … Read more
Problem Formulation Given a dictionary of key value pairs in Python. If you print the dictionary to the shell using print({‘a’: 1, ‘b’: 2}), the output is enclosed in curly brackets (braces) like so: {‘a’: 1, ‘b’: 2}. But you want the dictionary without brackets like so: ‘a’: 1, ‘b’: 2. How to print the … Read more
Do you need to create a function that returns a dictionary but you don’t know how? No worries, in sixty seconds, you’ll know! Go! ? A Python function can return any object such as a dictionary. To return a dictionary, first create the dict object within the function body, assign it to a variable your_dict, … Read more
Problem Formulation Given a Python dictionary d, and a list of dictionary keys. How to best determine the list of values associated to the keys? Formally, for each key in the input list, you want to add d[key] to the list of values. Here’s a minimal example: # Input: d = {‘alice’: 18, ‘bob’: 24, … Read more
Problem Formulation You create a namedtuple object in your code and you want to overwrite one of the attribute values like you’re used to for normal objects: But, unexpectedly, Python raises an AttributeError: can’t set attribute. ? What can you do? ? Let’s understand the reason this error occurs—after that, you’ll learn the best fixes. … Read more