Transcript ExcelIntro - Lyle School of Engineering

Introduction to Data Management
Lecture 2
1
Overview
• A little history
• Other computer-based spreadsheet
systems
• What is a spreadsheet?
• Types of Data
• KDD Process
Spreadsheet Beginnings
• Pencil and Paper
• ’78 Dan Bricklin – Harvard Business
School
– Use time sharing mainframe or pencil & paper
(and eraser too probably) for large project
– Neither were viable choices
• Created VisiCalc for PC of the day
– Apple II
Spreadsheet Beginnings
• In the beginning, VisiCalc could handle 5
rows x 20 columns – not extremely useful.
• Made more robust by Bob Frankston and
became a huge success
• Michael Kapor developed Lotus 1-2-3 in
early 80s
– Lotus was the first app to begin the ubiquitous
inclusion of computers in the business enviro.
Spreadsheet Beginnings
• Then enters Microsoft with Excel in ’84.
– Started out written for Apple Macintosh
because of windowing ability
– Moved to DOS (’87) and then to Windows
(’89)
– Remained the flagship windows product for 3
years
• Little competition until 1992
First Spreadsheet Program
http://www.bricklin.com/
Other Spreadsheets
http://www.gnome.org/projects/gnumeric/
Lotus 1-2-3 (older Windows ver.)
Open Office Calc
Excel 2003
What is a Spreadsheet
• Rows and columns intersecting in cells?
• Allows a 2D spatial relationship to be
imposed on data
=c1r1*c2r1
C1
R1
R2
C2
C3
1.1
2.2
2.42
4.4
3.3
14.52
=c1r2*c2r2
What is a spreadsheet?
• Pieces of data
and….
• Formulas to look at the data in a particular
way.
– Where information comes from
– Power lies in the ability to use complex
formulas.
Value Recalculation
• When a cell for which a calculated value
depends is changed, the calculated value
is automatically updated.
• How????
– Is the value of every cell in the whole
spreadsheet re-calculated?
Types of Data
• Different types of data require different
reactions to operators
– August 24, 2005 – 4 = ?
– August 24, 2005 – 25 = ?
• Some operators don’t operate on some
types of data
– Addition and string data
Types of Data
•
•
•
•
Textual
Numeric
Dates
Calculated values
– Contains references (absolute or relative) to
other cells in spreadsheet, workbook, etc.
KDD
• Knowledge Discovery in Data (KDD)
– Finding useful, possibly hidden, information in
data
Initial Set
of Data
Data
Required
Preprocessed
Data
Transformation
Knowledge/
Information
Model
Transformed
Data
KDD Process
• Selection
– Finding the data that you want to
analyze
• Preprocessing
– Erroneous data removed
– Missing data supplied or predicted
• Transformation
– “Massage” data in to most usable form
KDD Process
• Data Mining
– Apply data mining algorithms
– Discovery
• Interpretation/Evaluation
– Interpret what you’ve discovered
– Put in usable form
– Visualization techniques