Class: NamedVector

Inherits:
Object
  • Object
show all
Defined in:
lib/named_vector.rb

Overview

Vectors with named dimensions. Infinite dimensional objects with simple vector calculus operations defined.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*dims) ⇒ NamedVector

creates a new named vector

Parameters:

  • dims (Hash<String,Fixnum>, Hash<Symbol,Fixnum>, Array<String>, Array<Symbol>) —

    the dimensions to initialize the vectors with, either as a hash of assignments or simply the names of the dimensions.



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# File 'lib/named_vector.rb', line 12

def initialize(*dims)
	@vector = Hash.new
	@keys   = Set.new
	if dims && dims.first
		case dims.first
		when Hash
			hash = dims.first
			hash.keys.each {|d| modify_dimension(d, hash[d])}
		when String, Symbol, Fixnum
			@keys = Set.new(dims.map {|i| i.to_s})
			dims.each {|d| new_dimension(d)}
		end
	else
		@keys = []
	end
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(mid, *args) ⇒ Object (private)

:nodoc:



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# File 'lib/named_vector.rb', line 99

def method_missing(mid, *args) # :nodoc:
	mname = mid.id2name
	len = args.length
	if mname.chomp!('=')
		if len != 1
			raise ArgumentError, "wrong number of arguments (#{len} for 1)", caller(1)
		end
		modify_dimension(mname, args[0])
	elsif len == 0
		@vector.fetch(mname,0.0)
	else
		raise NoMethodError, "undefined method `#{mid}' for #{self}", caller(1)
	end
end

Instance Attribute Details

#keys ⇒ Object (readonly) Also known as: dimensions

Returns the value of attribute keys.



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# File 'lib/named_vector.rb', line 7

def keys
  @keys
end

Class Method Details

.add_dimension_iterator(obj) ⇒ Object

adds a dimension iterator (iterate through the keys) to a Hash or NamedVector

Parameters:

  • obj (Hash, NamedVector) —

    the object to add the method to.



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# File 'lib/named_vector.rb', line 47

def self.add_dimension_iterator(obj)
	obj.define_singleton_method(:each_dimension) do |&block|
		self.keys.each do |key|
			block.call(key)
		end
	end
end

.dot_product(a, b) ⇒ Object

Perform a dot product with another vector

Parameters:

  • a (Hash, NamedVector) —

    the vector or scalar to multiply this vector with.

  • b (Hash, NamedVector) —

    the vector or scalar to multiply this vector with.



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# File 'lib/named_vector.rb', line 64

def self.dot_product(a, b)
	sum    = 0.0
	if a.keys.length < b.keys.length
		a.each_dimension {|i| sum+=a[i]*b[i]}
	else
		b.each_dimension {|i| sum+=b[i]*a[i]}
	end
	sum
end

.from_mongo(doc) ⇒ Object

Mongo retrieval

Parameters:

  • doc (BSON::OrderedHash) —

    the mongo document to retrieve the vector from.



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# File 'lib/named_vector.rb', line 150

def self.from_mongo(doc)
	hash = {}
	doc["keys"].each_with_index do |k, index|
		hash[k] = doc["dimensions"][index]
	end
	self.new hash
end

Instance Method Details

#*(value) ⇒ Object

Perform a dot product with another vector

Parameters:

  • value (Hash, Fixnum, Float, NamedVector) —

    the vector or scalar to multiply this vector with. Scalar multiplication is destructive.



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# File 'lib/named_vector.rb', line 31

def *(value)
	case value
	when Fixnum, Float  #scalar multiplication product
		each_dimension {|i| @vector[i] = self[i]*value}
	when NamedVector #dot product
		NamedVector.dot_product(self, value)
	when Hash #dot product
		NamedVector.add_dimension_iterator(value)
		NamedVector.dot_product(self,value)
	else
		raise TypeError, "#{value.class} cannot be coerced to NamedVector."
	end
end

#[](key) ⇒ Object

fetches the value at the dimension specified

Parameters:

  • key (Symbol, String) —

    the dimension requested



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# File 'lib/named_vector.rb', line 83

def [](key)
	@vector.fetch(key.to_s,0.0)
end

#[]=(key, value) ⇒ Object

assigns a value at the dimension specified

Parameters:

  • key (Symbol, String) —

    the dimension requested

  • value (Fixnum, Float) —

    the assignment for this dimension



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# File 'lib/named_vector.rb', line 95

def []=(key,value)
	modify_dimension(key,value)
end

#dot_product(value) ⇒ Object

Perform a dot product with another vector

Parameters:

  • value (Hash, NamedVector) —

    the vector to multiply this vector with.



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# File 'lib/named_vector.rb', line 57

def dot_product(value)
	NamedVector.dot_product(self, value)
end

#each_dimension ⇒ Object

iterates through each dimension of a vector



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# File 'lib/named_vector.rb', line 75

def each_dimension
	@keys.each do |key|
		yield(key)
	end
end

#norm ⇒ Object

the Euclidean norm of a vector



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# File 'lib/named_vector.rb', line 133

def norm
	Math.sqrt(squared_norm)
end

#normalize ⇒ Object

normalizes the vector destructively.



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# File 'lib/named_vector.rb', line 138

def normalize
	current_norm = norm
	if current_norm > 0 then self*(1.0/current_norm) end
end

#squared_norm ⇒ Object

the squared Euclidean norm of a vector



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# File 'lib/named_vector.rb', line 126

def squared_norm
	norm    = 0.0
	each_dimension {|i| norm+=self[i]**2}
	norm
end

#to_mongo ⇒ Object

Mongo conversion



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# File 'lib/named_vector.rb', line 144

def to_mongo
	{"keys"=> @keys, "dimensions"=> @keys.map {|i| self[i]}}
end