Fuzzy-Logic

Fuzzy logic is a mathematical concept of fuzzy logical sets. An element of a fuzzy-set belongs to it in a range between zero and one.

read my work on this topic in german.

Installation

Add this line to your application's Gemfile:

gem 'fuzzy-logic'

And then execute:

$ bundle

Or install it yourself as:

$ gem install fuzzy-logic

Usage

A simple Fuzzy-Set

require 'fuzzy-logic'

its_near_christmas = FuzzyLogic::Set.new(1) { |time|
  # default output is zero
  o = 0.0

  # time has to be in december before or at the 24th
  if time.month == 12 and time.day <= 24 then
    # set is completly true when its 20th december or above
    o = 1.0 if time.day >= 20

    # set is fuzzy when its between 6th and 19th
    o = 1.0 - (24.0 - time.day)/(24.0 - 6.0) if time.day >= 6 and time.day < 20.0
  end

  # just the correct return
  o
}

its_near_christmas.get( Time.now )

its_near_christmas.support( Time.new(2013, 12, 8) ) # => true
its_near_christmas.support( Time.new(2013, 12, 6) ) # => false

tis_near_christmas.core( Time.new(2013, 12, 23) )   # => true
its_near_christmas.core( Time.new(2013, 12, 8) )    # => false

Use Fuzzy-Generators

The return is a normal Fuzzy-Set

require 'fuzzy-logic'

# generate a triangle
triangle = FuzzyLogic::Generate.triangle(10, 4) # range is (8..12) and mid is 10 (8 and 12 is zero)

# generate a trapezoid
trapez   = FuzzyLogic::Generate.trapezoid(10, 20, 30, 40) # ~support(10..40) and core(20..30)

# combinations
triangle_and_trapez = FuzzyLogic::Generate.and(triangle, trapez)
triangle_or_trapez  = FuzzyLogic::Generate.or( triangle, trapez)
not_in_trapez       = FuzzyLogic::Generate.not( trapez )           # not is just like this: Set.new { |n| 1 - trapez.get(n) }

for combinations there are also helpers

# shortcut of combinations
triangle_and_trapez = triangle.and trapez
triangle_or_trapez  = triangle.or  trapez
not_in_trapez       = trapez.not

Use Fuzzy-Collection

require 'fuzzy-logic'

temp = FuzzyLogic::Collection.new("temperature in °C") { |testvalue|
  o = true
  if not testvalue.is_a? Numeric then
    o = false
  elsif testvalue > 100 or testvalue < -100 then
    o = false
  end
  o
}

temp[:hot] = FuzzyLogic::Generate.trapezoid(25, 35, 100, 101)
temp[:cold] = FuzzyLogic::Generate.trapezoid(-101, -100, 5, 15)

temp[:cool_to_warm] = FuzzyLogic::Generate.and( FuzzyLogic::Generate.not(temp[:hot]), FuzzyLogic::Generate.not(temp[:cold]))

# or the short version
temp[:cool_2_warm] = temp[:hot].not.and temp[:cold].not

temp.get(20)
# => { :cool_to_warm => 1.0, :cool_2_warm => 1.0 }

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request