lst = [1,2,3,4,5,6,7,8] 
def sliding_window(elements, window_size):
	lst2 = []
	for i in range(len(elements)-window_size):
		a = sum(elements[i:i+window_size])/window_size
		lst2.append(a)
	return lst2

lst2 = sliding_window(lst, 3)
 
print(lst2)