Add mode.

1 files changed, 12 insertions, 1 deletions

diff --git a/math_utils.py b/math_utils.py
index 3a672da..156862a 100644
--- a/math_utils.py
+++ b/math_utils.py
@@ -2,10 +2,13 @@
 
 """Mathematical helpers."""
 
+import collections
 import functools
 import math
 from heapq import heappop, heappush
-from typing import List, Optional
+from typing import Dict, List, Optional, Tuple
+
+import dict_utils
 
 
 class NumericPopulation(object):
@@ -70,6 +73,14 @@ class NumericPopulation(object):
         count = len(self.lowers) + len(self.highers)
         return self.aggregate / count
 
+    def get_mode(self) -> Tuple[float, int]:
+        count: Dict[float, int] = collections.defaultdict(int)
+        for n in self.lowers:
+            count[-n] += 1
+        for n in self.highers:
+            count[n] += 1
+        return dict_utils.item_with_max_value(count)
+
     def get_stdev(self) -> float:
         """Returns the stdev so far in O(n) time."""