Python's mapping from keys to values: looking a value up, testing membership, adding and removing entries, iterating over keys and values, insertion order, and merging two dictionaries.
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The 8 lessons in this unit. Expand any one to see what it covers. Each unlocks when its own prerequisites are passed.
01
Dictionaries
12 questions
Learn how Python dictionaries store data as mutable key-value pairs, see how to create dictionaries with literal values, and use the len() function to determine their size.
Covers
Dictionaries overview
Creating a dictionary using literal values
Length of a dictionary
02
Accessing values in a dictionary
8 questions
Learn how to retrieve values from a Python dictionary using both square bracket notation and the .get() method, including how to handle missing keys without causing errors.
Covers
Dictionary lookup with []
Dictionary lookup with .get()
03
Dictionary membership
4 questions
Learn how to use the in and not in keywords to check whether a given key exists in a Python dictionary.
Covers
Dictionary membership
04
Modifying a dictionary
16 questions
Learn how to update, add, and delete dictionary entries in Python using assignment and the del statement, as well as the rules that determine which objects can be used as keys.
Covers
Updating a dictionary entry
Adding a new entry to a dictionary
Removing an entry from a dictionary
Dictionary keys
05
Iterating over a dictionary
12 questions
Learn how to iterate over a dictionary's keys, values, or key-value pairs in Python using built-in methods to access and process the information efficiently.
Covers
Iterating over a dictionary's keys
Iterating over a dictionary's values
Iterating over a dictionary's keys and values
06
Dictionary insertion order
4 questions
Python dictionaries preserve the order in which items are inserted, so iterating over a dictionary yields key-value pairs in insertion order rather than in an arbitrary sequence.
Covers
Dictionary insertion order
07
Merging two dictionaries
4 questions
Learn how to merge the key-value pairs of two dictionaries in Python using the .update() method, which adds new keys and overwrites existing ones in place.
Covers
Merging two dictionaries
08
Activity: library system
5 questions
Practise implementing a simple Python-based library management system by writing code to check book availability, add new books, lend books, list available books, and merge library collections.
Covers
Check book availability
Adding new books
Lending a book
Available books
Merging library collections
This unit is part of our Python Done Right learning path, which contains 100 lessons. Every one of them is drawn below.
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8 lessons in this unit
45 prerequisite lessons across the unit, counting every step back to the start
47 other lessons in the learning path - after this unit, or alongside it
Builds on: Assorted extras, Comparisons, Loops, Tuples
Leads to: Comprehensions, Sets, User-defined functions
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