CSC151 2007S, Class 42: Association Lists and Searching

* I feel like a broken record, but I consider it important enough that 
  I will continue to reserve time at the start of class for any comments 
  you have on campus climate.

Admin:
* We have another visitor today.
* EC for ...
  * Gene Gaub's concert Thursday at 11 a.m. in Herrick.
  * Thursday afternoon's CS Thursday extra on TCDB.
  * Lunch on Saturday from Neuroscience SEPC on 
    "Why and how to go to grad school in Neuroscience"
  * Symphonic Band on the 20th.  2pm See&Bring Louis
  * Discussion of Mental Health on Campus on the 22nd., 7-8:15 p.m.
* Assigned: The Project (due Friday the 25th.)
* Reading for Friday: Project Ideas. (Not ready until Friday.)

Overview:
* Storing information in tables.
* Representing table entries as lists.
* Representing tables as lists.
* Association list: Scheme's standard table representation.
* Implementing key association list procedures.
* Lab!

==THe Project===

* More fun making imagess
* YOu get nearly complete control
* But we put "fun" restrictions on
  * Don't make one, make a series of *related* images
    (image-series n width height)
* Use at least three different techniques

== Where we Are ==

* Ways of representing groups of data in Scheme
  * List
  * Vector
  * String (group of characters)
  * Tree
  * Files
* Today: Slight variant on list, along with some helpful procedures
* A simplified form of database
* Simple model: Table
  * A collection of keys with associated values
  * Given a key, find the corresopnding value

* Group key and value together into a list
  ("Rebelsky" "4410")
  ("chartreus" 127 240 128)
* Group lots of entries together into a list of entries
  (define silly-colors
    (list (list "charteus" 127 240 128)
          (list "read" 240 11 12)
          (list "chris" 120 120 6)))
* Is this useful?
* We can probably write aprocedure to search this list
* The assoc procedure does just that