Courses/Computer Science/CPSC 203/CPSC 203 2008Winter L03/CPSC 203 2008Winter L03 Lectures/Lecture 5

Lecture 5
Today we introduce a "dots and edges" model of spreadsheet, and emphsize that spreadheets are a general way or creating models using "functions" where a set of values from a "domain" is mapped into another set of valuables in the "range".


 * House Keeping
 * Course Lecture Schedule AND today's Spreadsheet on BB under course documents.
 *  MIDTERM: Tuesday February 26th 
 * Usual announcements
 * Extra Syllabus and Course Sheets at Front
 * Announcement for Natural Science Students
 * Term Project Intro and Tutorial Schedule on BB (quickly view term project intro).


 * Todays Goals
 * Quick Recap of last week's Dots and Edges Lecture (including re-def of Trees and Directed Acyclic Graphs).
 * Introduce a Dots and Edges model of spreadsheet, and use the Iris dataset to illustrate building a very simple analysis and classification model on some data.


 * Homework

Look up the basic functions and formats for:
 * Statistical Data Summarization: Summation, Mean, Standard Deviation, Mode, Median, Variance.
 * How "If Then" functions work.
 * How "Lookup" works.
 * Can you figure out the function to combine two pieces of text????


 * Spreadsheets 001
 * Two course themes: "Information in the large"; "Information in the small"
 * New glossary on spreadsheets
 * Spreadsheet data model
 * Spreadsheet Examples
 * Spreadsheet design principles

A Brief Cartoon History of Spreadsheets

 * Invented by Dan Bricklin in 1978, called Visicalc
 * A Brief History of Spreadsheets: http://dssresources.com/history/sshistory.html


 * Originally used for accounting and financial information
 * Lotus 1-2-3 developed by Mitch Kapor integrated charting, plotting and database-like capabilites, and spreadsheets became a general analysis and modelling tool.
 * Today's spreadsheets have added many bells and whistles, but essentially have the same functionality as Lotus 1-2-3 developed well over 20 years ago.

Lecture Glossary

 * Spreadsheet: Row by column array of cells. Values are passed from cell to cell.
 * Cell: "Atomic" unit of spreadsheet. In a cell there is data (values), formats (how cell looks) + data types (what kind of value: integer, text...etc)
 * Data Model: A model of relationships between pieces of data.
 * Operator & Function: Works on values to transform them.(i.e. +, -, X...)
 * Domain: Cells from which values are taken.
 * Range: Cells to which data is given.
 * Case: A unit of observation
 * Variable: An observed attribute
 * Properties -- the interface attributes of a cell: e.g. borders, fonts, shading, data types.
 * Value(s) -- the value a cell holds, which it can pass onto another cell.
 * Relative and Absolute Reference ("Location")

Spreadsheet Data Model

 * cell X -> cell Y
 * Domain X -> Range Y
 * Dots -- the cells
 * Edges -- Operators and Functions
 * Properties of a Spreadsheet Cell:
 * Format (i.e. colour, shading, background, font-size)
 * Type (i.e. data type)

A Spreadsheet is a "lattice" or "grid" of cells. Functions and operators allow values to be moved from cell to cell. A cell can not write back into itself. Essentially a spreadsheet is a very user friendly programming environment.

Spreadsheet Example
We illustrate the Spreadsheet data model via an illustrative spreadsheet
 * Iris Data Set (on BB course documents)
 * Highlighting Various parts of the spreadsheet
 * Calculations
 * A simple classification model
 * Some Charting examples

Homework
Look up the basic functions and formats for:
 * Statistical Data Summarization: Summation, Mean, Standard Deviation, Mode, Median, Variance.
 * How "If Then" functions work.
 * How "Lookup" works.
 * Can you figure out the function to combine two pieces of text????

Resources
The Elements of Spreadsheet Style. 1986. By J.M. Nevison (Great, cheap, book on spreadsheet design. Out of print, but easily ordered from Amazon).

A Brief History of Spreadsheets: http://dssresources.com/history/sshistory.html A nice little article on the origins of spreadsheets by some guys with too much facial hair.

Another overview on Spreadsheets is at: http://en.wikipedia.org/wiki/Spreadsheet