CSC 151.01, Class 41: Wrap Up

Overview

• Preliminaries
  • Notes and news
  • Upcoming work
  • Extra credit
  • Questions
• Comments on the final
• The subject matter(s) of the course
• Final PSA
• Final comments

Preliminaries

News / Etc.

• Sit where you’d like
• Today is my last day in CSC 151 this semester. (My son and the HS band are playing at the Iowa Bandmasters’ Association meeting on Friday.)
  • You are still expected to show up for class on Friday. Our mentors will take attendance.
  • Friday: Fill out evaluation forms (required). Go over problems from the final (optional).
• We have review sessions for the final on Wednesday of finals’ week.
  Details forthcoming.
• Some people received necessary extensions on the exam. Please do not discuss the exam with anyone until you get them back.
• I do intend to get all grades to you by Tuesday of finals’ week.
• Thanks for the recommendations for next semester’s students. They range from two words (“Start early”) to extended paragraphs.
• Reminder: Sunday is Mother’s day.
• Thank you S*y.

Upcoming work

• Cover sheets due NOW.
• Epilogues due TONIGHT.
• Final: Thursday or Friday afternoon of Finals Week (2pm-5pm) in this room.

Extra credit (Academic/Artistic)

• CSC 322 project presentations, Friday, 2-4 p.m. in 3821.
• Quantifying the effects of skill-based immigration - a two-country approach. TODAY at 4:15 in JRC 209.
• The Data Science Pipeline in Action: From Lung Cancer to Customer Churn. Friday at 4:15 in JRC 209.
• Networks and Foreign Policy Analysis: Relations, position and structure within the Clinton State Department. Tuesday at 4:15 p.m. in JRC 226.

Extra credit (Peer)

Extra credit (Recurring peer)

• Listen to KDIC Wednesdays at 6pm - Witty banter with other personalities and/or co-host. Also Indian, Arabic, and Farsi music.
  (Up to two units of extra credit.)
• Listen to KDIC Thursday at 7pm - Classic Rock. (60’s and 70’s)
• Peer editing with SS. Talk to SS about the details. Make your English Lit more literate.

Extra credit (Misc)

Other good things

• Sing happy birthday in class on Friday.

About quiz 13

• Problem 2 was confusing. I didn’t take off if you got it wrong or left it blank.
• People who did well on problem 2 got bonus points.

What are the parameters to the sorting routines?

• It varies. We’ve seen multiple implementations.
• Option 1: The list and a comparator. (sort numbers <)
• Option 2: The list, a get-key operation, and a comparator (sort students car string-ci>=?)
• For “sort in decreasing order”, I wanted either
  • (insertion-sort contacts car string-ci>=?)
  • (sort contacts (lambda (a b) (string-ci>=? (car a) (car b))))
  • (sort contacts (comparator string-ci>=? car))
• For sort by last name and first, I wanted either
  • (insertion-sort contacts (lambda (contact) (string-append (car contact) " " (cadr contact))) string-ci<=?)

Questions

Comments on the final

• Thursday at 2pm in this room.
• Different format than most exams: Paper (not computer), 4 problems (not 6), …
  • Kind of “extended quiz”
  • But you do get to bring notes.
• We may include vectors, trees, analysis/efficiency, code reading, code writing, lists, sorting, etc.
• We will not ask you to deal with files.
• In the past, most students who took the final finished in 90 minutes or less.

The subject matter(s) of the course

Problem solving

• Decompose a complex problem into smaller problems and combine the solutions back together. (To make a sandwich, we might think about “spread substance on bread” as a smaller problem.)
• You can solve the same problem in multiple ways.
  • Don’t accept your first solution as the only solution.
  • Reflect on whether you can solve the problem better.
  • We solve problems better when we can talk through the problems and solutions with a partner.
• You don’t solve every problem from scratch; there are patterns you develop and can apply to new problems.
• Don’t just jump in to your solution, plan ahead. Think about potential complexities or problems.
• Work backwards from goal to solution.

The Core of CS: Algorithms and data structures

• We’ve learned about sorting.
  • Insertion sort.
  • Um sort.
  • Merge sort.
  • Quick sort.
  • Selection sort.
  • Parameters to sorting, like the weird comparators we use for the built in sort.
  • We cover about four more in 207.
• We’ve learned above binary search trees.
• We can (and should) generalize algorithms so that they work for a broader set of inputs. E.g., if you can sort a vector of integers, you should be able to sort a vector of any type of values.
• Basic data structures: List, vectors, tables (lists of lists, vectors of vectors, etc.), trees, files (text and CSV)
• Core parts of algorithms: naming, subroutines, conditionals, sequencing, input and output, basic operations,

Functional programming

A different approach to thinking about programming and problem solving: centers around a mathematical approach to program design.

• “Functions are first-class values”; they can be parameters to other functions, they can be returned by other functions.
  • (o f g) - o takes two functions as input and returns a new function.
• Many common higher-order functions: map, reduce, filter.
• Side-effect-free programming. (Don’t change variables, don’t change the state of the system.)
• Anonymous procedures, created with lambda.
  • E.g., (map (lambda (x) (+ x (square x))) (iota 10))
• Other ways of building anonymous procedures with section.
• Recursion
  • Direct
  • Helper
  • Tail
  • Over lists, vectors, files, trees

Program and Software Design

• Test! Helps us identify errors. Helps us think more broadly about input and output.
• Program in pairs. It leads to more reliable code. (And usually ends up taking less time.)
• Untangling complex code. (Both the “Whatzitdo’s” and the complex code Sam sometimes inserts into readings. Also the code we wrote ourselves.)
• Document! It helps you figure out what the code will do. Good preconditions and postconditions not only explain your code to a client, they also help you learn more about the problem.
• We can write real programs. (Assignment seven.)
• Keeping your code readable.
• Recovering from errors/problems.

Scheme

• (you (need ((((lots)) of parentheses))))
• Evaluation strategy.
• How do do all of the six (seven?) key parts of algorithms.
• Between 50 and 100 different procedures (Sam thinks more.)
• You’ve learned most of core Scheme.

Data science

• Most data are messy; you need ways to clean your data
• Techniques for analyzing data.
• We can apply CS to other, more important, fields
• Manipulate complex data and present it
  • Numerically
  • Visually
• Work with real-world data which leads to useful understanding.

General thinking skills

• Practice thinking on your feet.
• Experience working with a wide variety of other people.
• Step-by-step approaches (back to the decomposition from problem solving)
• Ask for questions and ask for help.

And beyond

• Moral modeling: The value of family.
• “There’s more to life than CS (or any academic discipline)”
• Clarified that CS is not the right thing for me.
• Laugh.
• Support those around you.
• Be moderate.

Final PSA of the semester

• Don’t let the stress of finals’ week negatively affect you.
  • Get enough sleep.
  • If you decide to shut off your brain with substances, do so in moderation.
  • Don’t let academic honesty become an issue; our decision-making becomes less good at this time of the semester.
• Consent is essential.

Final comments