Practical Data Processing Using Map, Reduce and Select with Ruby
Practical Data Processing Using Map, Reduce and Select with Ruby
About the Book
This program prints out Pascal's triangle.
puts (0...10).reduce([[1]]) { |a,x|
a.unshift a.first.reduce([0,[]]) { |b,y|
[y,b.last << (b.first + y)]
}.last + [1]
}.reduce([]) { |c,z|
next [z[z.length/2].to_s.length*2,z.length,""] if c.empty?
[c[0],c[1], z.map { |j|
j.to_s.center(c[0])
}.join('').center(c[0]*c[1])+"\n#{c.last}"]
}.last
I found it on the internet at kellegous.com. How does such a complex program get encoded in 10 lines of code? Use this book to learn how to use map, reduce, and select with Ruby to solve data processing problems. Use this book along with a computer wth Ruby installed, a text editor, and the irb (interactive Ruby) prompt. As you read, type in the code, run the code and ponder the results. Tweak the code to test the code and the results. This book will walk you through problems and solutions which are effective because they use map, reduce, and select. You will gain a deeper understanding on how to break data processing problems into processing stages, each of which is understandable, debuggable, and composable, and how to combine the stages to solve your data processing problem.
About the Author
Table of Contents
-
- My Motivation
-
Audience
- Who This Book Can Help
- Who This Book Might Not Help
- Pre-requisites
-
Part 0 - Basic Ruby
- The command line
- Object Scope
- String
-
Array
- Special Methods
- Hash
- Block passing syntax
- Reading From Files
-
Part 1 Function Overview And Simple Examples
- Map
- Reduce
-
Simple reduce examples
- uniq
- reverse
- max
- Select
-
Part 2 Complex Solutions
-
Debugging Blocks for Map, Reduce and Select
- Debugging map blocks
- Debugging reduce blocks
- Debugging select blocks
- Fizzbuzz
- Sum of Odd Cubes
- Sort a list of names by surname
- Convert a list of names to CSV
- Generate a random list of names
- Clean A Data Set
- Annotate a sequence of sales with running total
- Pascal’s Triangle
- Reverse Polish Notation Parser
- Generate a list of team namebars
- Find Intersection Points of Two Functions
- Group by area code
- Sliding Window Average
- Denormalize a data set
- Pythagorean Triplets
-
Debugging Blocks for Map, Reduce and Select
-
Part 3 - Reverse Engineering Complex Solutions
- Solution For Pascal’s Triangle
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