stats.py

import math

class Stats:

	def __init__(self, dataset):
		self.dataset = dataset
		self.data_length = len(dataset)
		self.mean = sum(dataset) / self.data_length
		self.variance = None
		self.SD = None
		self.CV = None
		self.k = None
		self.current_result = None


	def curr_res(self, result):
		self.current_result = result

	def get_variance(self, exception=None):
		if self.dataset:
			variances = [ (i - self.mean) ** 2  for i in self.dataset ]
			total_sum_squares = round(sum(variances), 2)
			division_exception = -1 if exception == None else 0 
			variance = round(total_sum_squares / (self.data_length - division_exception ),2)
			
			self.variance = variance
			self.curr_res(variance)
		return self


	def get_standard_devi(self):
		if self.variance:
			SD = round(math.sqrt(self.variance), 2)
			self.SD = SD
			self.curr_res(SD)

			return self

	def get_CV(self, unit_num):
		CV = (self.SD * unit_num) / self.mean
		self.CV = CV
		self.curr_res(CV)
		return self

	def get_K(self, extra_set):
		lower_bound, upper_bound = extra_set
		if not self.SD:
			SD = self.standard_devi(self.variance(self.dataset))
			self.k = (lower_bound - self.mean) / SD
		else:
			self.k = (lower_bound - self.mean) / self.SD


		self.curr_res(self.k)
		return self


data = [12,14,11,18,10.5,11.3,12,14,11,9]
my_stat = Stats(data)
my_stat \
 .get_variance() \
 .get_standard_devi() \
 .get_CV(5) \
 .get_K((12.36, 15.35))

print(my_stat.current_result)