CSC 151.03, Class 31: Project introduction

Overview

• Preliminaries
  • Notes and news
  • Upcoming work
  • Extra credit
  • Quiz 10
  • Questions
• Quiz
• About the project
• Group composition and construction

News / Etc.

• Please try to keep the room straight.
• Quiz 9 returned.

Upcoming Work

• Reading for Monday: Association lists
  • Yes, it’s ready!
• No writeup for class 30.
• No writeup for class 31.
• Exam 3
  • Prologue due TONIGHT
  • Exam due Tuesday the 14th.
  • Cover pages due Wednesday the 15th.
  • Epilogues due Wednesday the 15th.

Extra credit (Academic/Artistic)

Extra credit (Peer)

• Eat at ISO food bazaar.
• Pioneer weekend walkins at 6pm today.

Extra credit (Misc)

Other good things

• Showvember tonight
• Drag

Quiz 10

Notes

• Did not go well.
• So we’ll go over it.
• I’m now dropping the two lowest quiz grades in calculating your final grade.

Problem 1

(cons
  (cons 5 10)
  (list 15
        20
        (cons 25 null)))

See whiteboard for drawing.

• Note: Drawing from inside out is generally a good strategy.

Result in Scheme

'((5 . 10) 15 20 (25))

Find the smallest value in a vector of real numbers.

We need to have a helper that keeps track of pos and smallest-so-far. We are going to write a kernel.

• Named let
• Write a separate helper procedure
• letrec

(define smallest-in-vector
  (lambda (vec)
    (let kernel ([pos 1]
                 [smallest-so-far (vector-ref vec 0)])
      (if (>= pos (vector-length vec))
          smallest-so-far
          (kernel (increment pos) 
                  (min smallest-so-far
                       (vector-ref vec pos)))))))

How do we fix this so that it doesn’t make the smallest inexact if it’s not already inexact?

• Keep track of the position rather than the value. But Sam is too lazy to implement that.
• Write better preconditions.
• Write tests for exact and inexact Sam really is lazy.
• Write inexact->exact in the base case. No!
• Rewrite min

Questions exam

Where should I start on problem 3?

1. Make a list of all the things you need for it to be a BST. Two options: Empty tree. Nonempty tree. i. Is it a node? ii. Does it contain a string? iii. Is the left tree a BST? (Trust the magic recursion fairy.) iv. Is the right tree a BST? (TTMRF); v. c; vi. d.

Use and to group things together for the nonempty tree case.

Question in prep for next quiz

Quiz

Ooh! A tree problem. That will be helpful when I solve problem 3 on the exam.

About the project

• Do something interesting of your choice within constraints
  • New and different data set
  • Requires some processing/munging/whatever you want to call
  • With a novel algorithm that does something to help you understand the data
• Examples
  • Literature classifier
  • Text generation
  • Something similar to cancer cell identification.
  • A set of tools for dealing with a data set. (E.g., …)
• Goals
  • Time-boxed: 8-10 hours per person over two+ weeks
  • Ideal group size: 3 (or 2 or 4 or 1)
• For a week from Monday: Find the data set and Write a proposal
  • Describe set
  • Describe your intended goals with the data set
    • What you think you can do
    • What would satisfice
    • Reach goal
  • Describe the algorithms you will be generating

Group composition and construction