Class: Eventsims::Calculate

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

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ Calculate

Returns a new instance of Calculate.



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# File 'lib/eventsims/discrete.rb', line 53

def initialize(*args)
	''' Initialising the instances '''
	#Checking for valid arguments and value assignment
	@args = args

	if args.length == 3
		@steps = args[2]
	
	elsif args.length == 2
		@steps = 1

		else
			raise "Invalid arguments: must be 2 or 3 -->  Outcome , Cummulative probability, optional: steps"
		end

	@outcome, @cum_prob, @probability = args[0], args[1], []

		# Checks in case user hasn't inputted the right information #Error checks for invalid inputs
		@last_cum = @cum_prob.at(-1)

		if @outcome.size != @cum_prob.size
			raise "'prob' arguments must be of same length"

		elsif @last_cum != 1
			raise "last value of 2nd argument must be 1"
	end

	args[1].each{|i|
			raise "cummulative probability must be between 0 and 1" if 0 > i or i > 1 }
end

Instance Method Details

#discreteemp ⇒ Object

Generates a discreteEmp for the given outcome



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# File 'lib/eventsims/discrete.rb', line 100

def discreteemp()
	'''returns a random number from the outcome list'''
	#--- generating a random number based on discreteemp
	
	emplist = []

	def twoargs()
		count, number = 0, rand()

		while count < (@cum_prob).size
			if @cum_prob[count] < number and number <= @cum_prob[count+1]
				return Eventsims.trimval(@outcome[count+1])
			
			elsif 0 <= number and number <= @cum_prob[0]
			 	return Eventsims.trimval(@outcome[0])
			end
			count+=1
		end
	end

	if @args.length == 2
		return Eventsims.trimval(twoargs())

	elsif @args.length == 3
		@amount, increment = @args[2], 0
		if @amount.is_a? (String )
			raise "Only integers allowed as third argument"
		end
		if @amount == 1
			return Eventsims.trimval(twoargs())

		else
			#try:
				while increment < @amount
					generated = twoargs()
					if generated.is_a?(Float)
						generated = Eventsims.trimval(generated)
					end
					emplist << (generated)
					increment +=1
				end
			
			return emplist
		end
	end
end

#estmean ⇒ Object 



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# File 'lib/eventsims/discrete.rb', line 191

def estmean()
	return expectval
end

#eststddev ⇒ Object

Calculates the estimated variance of the given lists



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# File 'lib/eventsims/discrete.rb', line 171

def eststddev()
	'''returns estimated variance of the outcome'''
	#arguments are: [outcomes], [cummulative probabilities], optional: float(steps)]

	mean = expectval / @steps
	increment, occurtimes = 0, 0
	
	while increment < @cum_prob.size
		occurtimes += @probability[increment] * (@outcome[increment] - mean)**2
		increment +=1
	end

	if @args.size == 2
		return Eventsims.trimval((occurtimes)**0.5)

	elsif @args.size == 3
		return Eventsims.trimval(occurtimes**0.5 * @steps**0.5)
	end
end

#estvar ⇒ Object

Calculates the estimated standard deviation of the given lists



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# File 'lib/eventsims/discrete.rb', line 196

def estvar()
	''' Returns the estimated standard deviation of the outcome'''
	#arguments are: [outcomes], [cummulative probabilities], optional: float(steps)]
	variance = eststddev**2
	return Eventsims.trimval(variance)
end

#expectval ⇒ Object

Calculates the expectation value given its outcome and cummulative probability



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# File 'lib/eventsims/discrete.rb', line 148

def expectval()
	''' returns the expectation value of the outcomes'''
	
	expectation, increment, probability = 0,0, prob()
	
	while increment < @cum_prob.size
		expectation += probability[increment] * @outcome[increment]
		increment += 1
	end

	if @args.size == 2
		return Eventsims.trimval(expectation)

	elsif @args.size == 3
		expectation *= @steps
		return Eventsims.trimval(expectation)

	else
		raise "arguments must be two or three"
	end
end

#prob ⇒ Object

Calculates the probability of an outcome given its cummulative probability



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# File 'lib/eventsims/discrete.rb', line 84

def prob()
	''' Returns a probability given its cummulative probability '''

	# Starting variables
	y = 1; @probability.push(@cum_prob[0])

	while y < @cum_prob.size
		@probability << (@cum_prob[y] - @cum_prob[y-1]).round(4)
		y+=1
	end

	return Eventsims.trimval(@probability)
end

#twoargs ⇒ Object 



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# File 'lib/eventsims/discrete.rb', line 106

def twoargs()
	count, number = 0, rand()

	while count < (@cum_prob).size
		if @cum_prob[count] < number and number <= @cum_prob[count+1]
			return Eventsims.trimval(@outcome[count+1])
		
		elsif 0 <= number and number <= @cum_prob[0]
		 	return Eventsims.trimval(@outcome[0])
		end
		count+=1
	end
end