Class 10: Detecting Gravitational Waves, Programming with Lists

cs1120: Introduction to Computing
Explorations in Language, Logic, and Machine
University of Virginia, Spring 2016

http://xplorecs.org/class10

Class 10:
Gravitational Waves
Making Triples from Pairs
Making Lists
Programming with Lists

Transcript

1. cs1120 Spring 2016 David Evans University of Virginia Class 10: Programming with Data Introduction to Computing: Explorations in Language, Logic, and Machines
2. Plan Making Lists from Pairs Programming with Lists Project 2 is Due Monday: Good Project 2 is automatic Green Belt pass! Yuchi has scheduled extra office hours Sunday, 3-4:30pm (also has regular office ours today right after class) If you don’t complete Yellow Belt by Sunday, additional steps will be necessary.
4. Hanford, Washington Livingston, Louisiana
5. Hanford, Washington Livingston, Louisiana
8. https://versions.ligo.org/cgit/
9. https://versions.ligo.org/cgit/pycoh/tree/pycoh/signals.py
11. Data Abstraction
13. Are pairs enough?
14. Making a Triple
15. Making a Quadruple
16. Multuples A Quintuple is a Pair where the second part is a Quadruple A Sextuple is a Pair where the second part is a Quintuple A Septuple is a pair where the second part is a Sextuple An Octuple is group of octupi A ? is a Pair where the second part is a …? 15
17. Lists List ::= Element List 16 A List is a Pair where the second part is a List. One big problem: how do we stop? This only allows infinitely long lists!
18. Lists List ::= Element List List ::= 17 A List is either: a Pair where the second part is a List or, empty It’s hard to write this!
19. Null List ::= Element List List ::= 18 A List is either: a Pair where the second part is a List or, empty (None) None None here is like ε for BNF grammars!
20. With Python lists: p = [element, …] first = p[0] rest = p[1:] Python tutor link
21. Recursive Procedures on Lists 1. Be very optimistic! 2. Determine the base case: smallest version of the problem, where you know the answer right away 3. Recursive case: combine the result of doing something with the first element, with the recursive call on the rest of the list
22. def list_length(lst): # Returns the number of elements in lst.
23. def list_length(lst): # Returns the number of elements in lst. With standard Python lists: len(lst)
24. Charge • Project 2 is due Monday • We are focusing on recursive ways to define functions now because they are general, universal, and elegant – But, not the “Pythonic” way to do things…we will see other ways to define these same functions