dict
Mathematical Programming with Python
https://people.sc.fsu.edu/~jburkardt/classes/...
python_2025/dict/dict.html

dict: the Python dictionary data type is a very clever and useful extension of the array. Instead of a numeric index, a dictionary uses a keyword to find an item. It is easy to add new entries to the dictionary. We will see that a dictionary can be used to make our Collatz conjecture code much more efficient, so that our data begins to resemble a tree structure with each number pointing to its successor in the sequence.

Lecture notes:

• dict.pdf

• collatz_test.py, uses a dict to keep track of which Collatz values have already been calculated.
• json_test.py, reads a Collatz dict from a JSON file and updates it; reads information from a JSON file and reports it.
• states_test.py, uses a dict to store pairs of state names and state capitals.