Held: Wednesday, 2 December 2015

Back to Outline 50 - Project Assessment: Algorithms. On to Outline 52 - An Introduction to Sorting.

Summary

We continue our explorations of binary search, grounding our explorations in practice.

Related Pages

• Reading: Searching
• Lab: Binary Search
• EBoard 51 (Source 51)

Overview

• Exploring the search API.
• Remaining questions.

Administrivia

• New partners for today! (Same partners on Friday.)
• We will continue crits of your artwork on Friday.
• I'll be leaving class at 10:30 for a personal event.
• Review sessions Wednesday (TONIGHT) at 8pm, Thursday at 10am, Thursday at 8pm.

Upcoming Work

• No reading for Friday.
• Today's Lab writeup (due Monday)
  • Email to grader-151-01@cs.grinnell.edu
  • Subject: CSC 151 Lab Writeup Class 51 (Your Names)
  • Exercises:
• Quiz Friday: Analysis, Association Lists, Binary Search.
• Exam 4 prologue due Friday, Dec. 4.
• Exam 4 due Monday, Dec. 7. Email it to me as an attachment. Use your random number form last time, or grab a new one.
• Exam 4 cover sheet due Tuesday, Dec. 8.
• Exam 4 epilogue due Tuesday, Dec. 8.

Extra Credit Opportunities

• If possible, send me these in advance.

Academic

• Any visit to the current show in the Faulconer gallery.
• Campus Town Hall on Student Well-Being, Noon or 7:30 p.m. on Wednesday, December 2 in JRC 101. TODAY!
• Eliza Harrison presents Early Sonia Delaunay: The Avant-Garde at Home, an Art History MAP under the direction of Professor Anger. 4:15 pm, Wednesday, December 2nd, Bucksbaum 242 with coffee and fruit. TODAY!
• Future of the Libraries Talk, December 3, Noon, JRC 101. TOMORROW!
• Human Computers at NASA, 8 p.m., December 3, ARH 302 TOMORROW!
• CS Extras, Thursday, Summer Research at UMich, 4:15 p.m. 3821. TOMORROW!

Peer Support

• Dance Ensemble, Friday and Saturday at 7:30 p.m.
• Women's Basketball vs. St. Norbert, Dec. 5 at 3:00 p.m.
• One-act Festival Dec. 5 at 2pm and & Dec 6 at 7 p.m.
• Choir Concert, Dec. 6 at 2pm in Herrick.
• Sweater party, Saturday at 9pm. Wear ugly christmas sweaters and dance. Will include appropriate and inappropriate beverages.
• Deshowber/Showcember, Friday, Gardner.

Regular Peer Support

• Pals of PALS, pals@grinnell.edu, normally Saturday at 7:45 am (breakfast included; felines only), and Mondays at 4:45. Requires sign up in advance. MORE HELP NEEDED!
• Socrates Cafe', Saturdays, Younker, 2pm.
• Pun Club, Saturdays, 4pm, Way over Younker.

Misc.

• Sub free this weekend.

Upcoming Peer Support

• Women's Basketball vs. Carroll, Dec. 12 at 3:00 p.m.

Other Good Things (No Extra Credit)

• Swim Meet December 4/5.
• Jingle Bell Holiday December 4. I may not be there (swim meet), I'll try to find a way to treat you to tenderloins / chicken / potatoes.

Exploring the Search API

Suppose we have data for various students on campus: Last Name (string), First Name (string), Graduation Year (integer), Box Number (integer), and Phone number (string). We might search by any of the four criteria (and by other criteria) and we might therefore order in various ways.

(define people
  (vector 
    ("Aanderson" "Aan"    2017 4114 "x4410")
    ("Brown"     "Bruin"  2016 8123 "x9000")
    ("Doe"       "J"      2018 9999 "none")
    ("Smith"     "Kieran" 2015 4112 "x9231")
    ("Taylor"    "Mic"    2017 1234 "x0001")))

• Right now, we have things sorted by last name (and, surprisingly, by first name), so we might search by last name (or by first name).
• If we wanted to search by year, we'd order by year (although that's not likely to give particularly useful results).
• If we wanted to search by box number, we'd order by box number.
• Our search algorithm needs to know how to find the key in an entry
  • Last name: car
  • First name: cadr
  • Year: caddr
  • Box number: cadddr
• Our search algorithm needs to know how the keys are ordered
  • Traditionally, strings are ordered alphabetically
  • Traditionally, numbers are ordered numerically, from smallest to largest
• So our binary search algorithm needs four parameters:
  • The vector to search
  • The key to search for
  • The instructions for getting a key from each element
  • The mechanism used to order the elements
• All of this is a bit more complicated if we have a compound key, such as "last name plus first name plus phone number"

Lab

• Do the lab
• Be prepared to reflect.