1 20-IteratorsGenerators

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1.1 Screencasts

• Password for the Vimeo videos is in Zulip chat.

• https://vimeo.com/536021820

• Tip: If anyone want to speed up the lecture videos a little, inspect the page, go to the browser console, and paste this in:
  document.querySelector('video').playbackRate = 1.2

  “I don’t think necessity is the mother of invention. Invention . . . arises directly from idleness, possibly also from laziness. To save oneself trouble…”

  Agatha Christie

1.2 Some syntactic sugar today

https://en.wikipedia.org/wiki/Syntactic_sugar

1.3 Code

Code (to be stepped through in spyder and/or pudb):
* 20-IteratorsGenerators/iter_00_comprehensions.py
* 20-IteratorsGenerators/iter_01_iterators.py
* 20-IteratorsGenerators/iter_02_generators.py

1.4 List, set, and dictionary comprehensions

A sweet and elegant way to create lists, sets, and dictionaries
* https://docs.python.org/3/tutorial/datastructures.html#list-comprehensions
* https://realpython.com/list-comprehension-python/
* https://www.digitalocean.com/community/tutorials/understanding-list-comprehensions-in-python-3
* https://www.geeksforgeeks.org/comprehensions-in-python/
* https://www.geeksforgeeks.org/nested-list-comprehensions-in-python/
* https://www.learnpython.org/en/List_Comprehensions
* https://www.python-course.eu/python3_list_comprehension.php

1.5 Iterators and generators

• https://anandology.com/python-practice-book/iterators.html
• https://docs.python.org/3/tutorial/classes.html#generators
• https://docs.python.org/3/tutorial/classes.html#iterators
• https://nvie.com/posts/iterators-vs-generators/
• https://realpython.com/introduction-to-python-generators/
• https://wiki.python.org/moin/Generators
• https://wiki.python.org/moin/Iterator
• https://www.datacamp.com/community/tutorials/python-iterator-tutorial
• https://www.geeksforgeeks.org/generators-in-python/?ref=lbp
• https://www.geeksforgeeks.org/iterators-in-python/
• https://www.learnpython.org/en/Generators
• https://www.python-course.eu/python3_generators.php
• https://www.python-course.eu/python3_iterable_iterator.php
• https://www.python.org/dev/peps/pep-0234/
• https://www.python.org/dev/peps/pep-0255/
• https://www.w3schools.com/python/python_iterators.asp

1.5.1 Iterators

• An iterable object is an object that implements _iter_, which is expected to return an iterator object.

• An iterator is an object that implements next, which is expected to return the next element of the iterable object that returned it, and raise a StopIteration exception when no more elements are available to be iterated through.

• In the simplest case, the iterable will implement next itself and return self in _iter_.

• You can iterate across iterables using for loops, and/or you can use them to construct objects like lists directly using the constructor of the data structure.

  “Never put off till tomorrow what may be done the day after tomorrow just as well.”
  ~ Mark Twain

  “I never put off till tomorrow what I can possibly do the day after.”
  ~ Oscar Wilde

1.5.2 Generators

• Generator functions allow you to declare a function that behaves like an iterator, e.g., it can be used in a for loop.
• Generator functions are a special kind of function that return a lazy iterator, which procrastinates its computation of future elements to be iterated.
• These are objects that you can loop over like a list.
• However, unlike lists, lazy iterators do not store their contents in memory, and only do the computation to generate the next item when asked for it.

1.6 Summary of today’s vocabulary

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