#!/usr/bin/env python3
+"""Mathematical helpers."""
+
import functools
import math
+from heapq import heappop, heappush
from typing import List
-from heapq import heappush, heappop
class RunningMedian(object):
>>> median.add_number(5)
>>> median.get_median()
5
+ >>> median.get_mean()
+ 5.2
+ >>> round(median.get_stdev(), 2)
+ 6.99
"""
def __init__(self):
self.lowers, self.highers = [], []
+ self.aggregate = 0.0
- def add_number(self, number):
+ def add_number(self, number: float):
if not self.highers or number > self.highers[0]:
heappush(self.highers, number)
else:
heappush(self.lowers, -number) # for lowers we need a max heap
+ self.aggregate += number
self.rebalance()
def rebalance(self):
elif len(self.highers) - len(self.lowers) > 1:
heappush(self.lowers, -heappop(self.highers))
- def get_median(self):
+ def get_median(self) -> float:
if len(self.lowers) == len(self.highers):
- return (-self.lowers[0] + self.highers[0])/2
+ return (-self.lowers[0] + self.highers[0]) / 2
elif len(self.lowers) > len(self.highers):
return -self.lowers[0]
else:
return self.highers[0]
+ def get_mean(self) -> float:
+ count = len(self.lowers) + len(self.highers)
+ return self.aggregate / count
+
+ def get_stdev(self) -> float:
+ mean = self.get_mean()
+ variance = 0.0
+ for n in self.lowers:
+ n = -n
+ variance += (n - mean) ** 2
+ for n in self.highers:
+ variance += (n - mean) ** 2
+ return math.sqrt(variance)
+
def gcd_floats(a: float, b: float) -> float:
if a < b:
3.141
"""
- assert decimals > 0 and decimals < 10
- multiplier = 10 ** decimals
+ assert 0 < decimals < 10
+ multiplier = 10**decimals
return int(n * multiplier) / multiplier
# This is checked so that we can skip middle five numbers in below
# loop
- if (n % 2 == 0 or n % 3 == 0):
+ if n % 2 == 0 or n % 3 == 0:
return False
i = 5
while i * i <= n:
- if (n % i == 0 or n % (i + 2) == 0):
+ if n % i == 0 or n % (i + 2) == 0:
return False
i = i + 6
return True
if __name__ == '__main__':
import doctest
+
doctest.testmod()