Class: ProbabilityToFriendlyString::FriendlyProbability

Inherits:
Object
  • Object
show all
Includes:
Comparable
Defined in:
lib/probability_to_friendly_string.rb

Overview

Represents probability represented in a friendly manner.

Constant Summary collapse

@@fractionsData = 
nil
@@friendlyDescriptionValues = 
[0.005, 0.02, 0.08, 0.15, 0.2, 0.45, 0.55, 0.7, 0.8, 0.85, 0.9, 0.95, 0.995]
@@friendlyDescriptionStrings = 
[
          "Hard to imagine",
          "Barely possible",
          "Still possible",
          "Some chance",
          "Could happen",
          "Perhaps",
          "Flip a coin",
          "Likelier than not",
          "Good chance",
          "Probably",
          "Quite likely",
          "Pretty likely",
          "Very likely",
          "Almost certainly",
]

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(numerator, denominator, friendlyDescription, friendlyString = nil) ⇒ FriendlyProbability

Returns a new instance of FriendlyProbability.



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# File 'lib/probability_to_friendly_string.rb', line 26

def initialize(numerator, denominator, friendlyDescription, friendlyString = nil)
    @numerator = numerator
    @denominator = denominator
    @friendlyDescription = friendlyDescription
    if friendlyString
        @friendlyString = friendlyString 
    else
        @friendlyString = "%d in %d" % [numerator, denominator]
    end
end

Instance Attribute Details

#denominator ⇒ Object (readonly)

Returns the value of attribute denominator.



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# File 'lib/probability_to_friendly_string.rb', line 5

def denominator
  @denominator
end

#friendlyDescription ⇒ Object (readonly)

Returns the value of attribute friendlyDescription.



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# File 'lib/probability_to_friendly_string.rb', line 5

def friendlyDescription
  @friendlyDescription
end

#friendlyString ⇒ Object (readonly)

Returns the value of attribute friendlyString.



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# File 'lib/probability_to_friendly_string.rb', line 5

def friendlyString
  @friendlyString
end

#numerator ⇒ Object (readonly)

Returns the value of attribute numerator.



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# File 'lib/probability_to_friendly_string.rb', line 5

def numerator
  @numerator
end

Class Method Details

._addFraction(fractionsData, numerator, denominator) ⇒ Object 



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# File 'lib/probability_to_friendly_string.rb', line 37

def self._addFraction(fractionsData, numerator, denominator)
    fractionsData << [numerator.to_f/denominator, numerator, denominator]
end

._createFractionsData ⇒ Object 



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# File 'lib/probability_to_friendly_string.rb', line 40

def self._createFractionsData
    if @@fractionsData
        return
    end
    fractionsData = []
    (2..10).each do |d|
        (1..d).each do |n|
            if n.gcd(d) == 1
                _addFraction(fractionsData, n, d)
            end
        end
    end
    [12, 15, 20, 30, 40, 50, 60, 80, 100].each do |d|
        _addFraction(fractionsData, 1, d)
        _addFraction(fractionsData, d - 1, d)
    end
    @@fractionsData = fractionsData.sort
end

.fromProbability(f) ⇒ FriendlyProbability

Creates a FriendlyProbability from a double

Parameters:

  • f (Numeric) —

    a probability between 0 and 1

Returns:



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# File 'lib/probability_to_friendly_string.rb', line 63

def self.fromProbability(f)
    if f < 0 or f > 1
        raise RangeError, "f is less than 0 or greater than 1"
    end
    # index of the least element > f
    index = @@friendlyDescriptionValues.bsearch_index {|x| x > f}
    if index.nil?
        index = @@friendlyDescriptionStrings.length - 1
    end
    friendlyDescription = @@friendlyDescriptionStrings[index]
    if f == 0
        return FriendlyProbability.new 0, 1, friendlyDescription
    elsif f == 1
        return FriendlyProbability.new 1, 1, friendlyDescription
    elsif f > 0.99
        return FriendlyProbability.new 99, 100, friendlyDescription, ">99 in 100"
    elsif f < 0.01
        return FriendlyProbability.new 1, 100, friendlyDescription, "<1 in 100"
    end

    FriendlyProbability._createFractionsData
    # index of the least element > f
    right = @@fractionsData.bsearch_index {|x| x[0] > f}
    if right
        left = right - 1
    else
        left = @@fractionsData.length - 1
    end
    if (left == (@@fractionsData.length - 1) or (left >= 0 and f - @@fractionsData[left][0] < @@fractionsData[right][0] - f))
        return FriendlyProbability.new @@fractionsData[left][1], @@fractionsData[left][2], friendlyDescription
    else
        return FriendlyProbability.new @@fractionsData[right][1], @@fractionsData[right][2], friendlyDescription
    end
end

Instance Method Details

#<=>(another_friendly_string) ⇒ Object 



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# File 'lib/probability_to_friendly_string.rb', line 102

def <=>(another_friendly_string)
    if self.numerator < another_friendly_string.numerator
        -1
    elsif self.numerator > another_friendly_string.numerator
        1
    end
    if self.denominator < another_friendly_string.denominator
        -1
    elsif self.denominator > another_friendly_string.denominator
        1
    end
    if self.friendlyDescription < another_friendly_string.friendlyDescription
        -1
    elsif self.friendlyDescription > another_friendly_string.friendlyDescription
        1
    end
     if self.friendlyString < another_friendly_string.friendlyString
        -1
    elsif self.friendlyString > another_friendly_string.friendlyString
        1
    else
        0
    end
end

#to_s ⇒ Object 



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# File 'lib/probability_to_friendly_string.rb', line 98

def to_s
    return "#{@numerator}/#{@denominator} (text: \"#{@friendlyString}\", description: \"#{@friendlyDescription}\")"
end