Held: Wednesday, 12 February 2014

Back to Outline 14 - Transforming Images. On to Outline 16 - Programming the GIMP Tools.

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 (Source) (HTML) (PDF)

Overview

• Context: What and why lists?
• Building lists.
• Mapping lists.
• Other list operations.

Administrivia

• Friday's reading: The GNU Image Manipulation Program and Scripting the Gimp Tools
• Lab writeup: Exercise 5
  • Subject: CSC 151.02 Writeup 11: Lists of Drawings (YOUR NAME)
  • Due Friday.
• I won't be able to hold a review session this week. Sorry.
• We'll spend a few minutes looking at some issues from yesterday's lab.
• Extra credit:
  • Thursday extra, Thursday @ 4:30 p.m., Sci. 3821, Red/Black trees.
  • Opera Iowa: The Elixir of Love, Thursday, 7:30, Roberts
  • CS Table Friday @ noon: Law, Order, and Computers

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.