Held: Wednesday, 25 September 2013

Back to Outline 15 - Transforming Images. On to Outline 17 - Anonymous Procedures.

Summary

Today we explore Scheme's list data structure and some ways to use lists to make interesting images.

Related Pages

• Reading: Making and Manipulating Homogeneous Lists
• Lab: Making and Manipulating Lists of Drawings
• EBoard (HTML) (PDF)

Overview

• Context: What and Why Lists?
• Building Lists.
• Mapping Lists.
• Other List Operations.
• Lab.

Administrivia

• I realize that there's crud going around campus. Do yourself and your classmates a favor and get rest if you are sick. Drop me a note to let me know.
• We have a new homework assignment. The only thing my random procedure paid attention to was whether or not you asked to work alone.
• Continue lab partners!
• I'm going to have an optional class this Thursday at 1:15 (and, I hope, most Thursdays) as a chance to talk to folks about more things that might be useful or interesting.
  • We won't have the optional class Thursday the 3rd, as I'll be unavailable.
• Work for Friday:
  • Review the homework assignment
  • Read Anonymous Procedures
  • Do lab writeup 5 if you haven't done so already.
  • Do lab writeup 6: Etercise 5 from the Lists of Drawings Lab
    • Due before class on Friday.
    • Title: "CSC 151.02 Lab Writeup 6: Lists (NAME)".
• EC Opportunities:
  • CS Extras Thursday @ 4:30: Jennelle Nystrom on working at Microsoft
  • CS Table Friday (The Story of Mel)
  • Football, 1pm, Saturday against Beloit
  • Orchestra, 2pm, Saturday, Sebring-Lewis or somewhere similar
  • Folksyish music with Seth at Relish, Wednesday at 10pm
  • Knitting club, Saturday at 10am. Do good and have fun!
  • More ...?
• Other things you might do (no EC, but possibly a good idea)
  • Facing the Bear, 7-9 pm Wednesday
  • Swipe your P-Card at the Football or Soccer game
  • Poweshiek CARES March Thursday. Leave from Herrick at 4:45 p.m. Email chenjerem@gmail.com for more info. I can also forward you the email.
  • Poweshiek CARES March Thursday, Oct. 3. Meet at Drake Library at 5 p.m.
  • GHS Homecoming Parade Thursday, Oct. 3. If you've never seen a small-town homecoming parade, it's worth it. (And last year's homecoming queen is a current Grinnell student.)

Context: What Are Lists?

• Issue: We'd like to make images with lots and lots of similar shapes.
• Problem: How to do so systematically.
• Solution: Scheme's list data structure and some related procedures.
• We're learning a new type, so it's useful to figure out some basic issues.

Building Lists

• (list val1 val2 ... valn)
• (make-list n value)
• (iota n)

Mapping Lists

• Basic operation: (map func lst). Apply a function to each element of a list.
• For images, we'll find it easier to do something like
  (map drawing-transform list-of-drawings list-of-values)

Other List Operations

• (append *lst1* *lst2*) - join two lists
• (reverse *lst*) - just what it sounds like
• (list-take *lst* *n*) - take the first n elements of a list
• (list-drop *lst* *n*) - drop the first n elements of a list

Lab

• Do the lab.
• Be prepared to reflect.