From 1ff5dde5b037f8da4c9d5a65e2d7ad2f6715ff60 Mon Sep 17 00:00:00 2001
From: Scott Gasch <scott@gasch.org>
Date: Fri, 11 Feb 2022 11:40:38 -0800
Subject: [PATCH] Add mode.

---
 histogram.py  | 14 +++++++++-----
 math_utils.py | 13 ++++++++++++-
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/histogram.py b/histogram.py
index dd47319..3796470 100644
--- a/histogram.py
+++ b/histogram.py
@@ -122,9 +122,11 @@ class SimpleHistogram(Generic[T]):
         )
         if len(sigma_label) > details.max_label_width:
             details.max_label_width = len(sigma_label)
-        bar_width = width - (details.max_label_width + 16)
+        bar_width = width - (details.max_label_width + 17)
 
         for (start, end), pop in sorted(self.buckets.items(), key=lambda x: x[0]):
+            if start < details.lowest_start:
+                continue
             label = f'[{label_formatter}..{label_formatter}): ' % (start, end)
             bar = bar_graph(
                 (pop / details.max_population),
@@ -141,12 +143,14 @@ class SimpleHistogram(Generic[T]):
         txt += '-' * width + '\n'
         txt += sigma_label.rjust(details.max_label_width)
         txt += ' ' * (bar_width - 2)
-        txt += f'Σ=(100.00% n={self.count})\n'
+        txt += f'     pop(Σn)={self.count}\n'
         txt += ' ' * (bar_width + details.max_label_width - 2)
-        txt += f'mean(μ)={self.stats.get_mean():.3f}\n'
+        txt += f'     mean(x̄)={self.stats.get_mean():.3f}\n'
         txt += ' ' * (bar_width + details.max_label_width - 2)
-        txt += f'p50(η)={self.stats.get_median():.3f}\n'
+        txt += f' median(p50)={self.stats.get_median():.3f}\n'
         txt += ' ' * (bar_width + details.max_label_width - 2)
-        txt += f'stdev(σ)={self.stats.get_stdev():.3f}\n'
+        txt += f'    mode(Mo)={self.stats.get_mode()[0]:.3f}\n'
+        txt += ' ' * (bar_width + details.max_label_width - 2)
+        txt += f'    stdev(σ)={self.stats.get_stdev():.3f}\n'
         txt += '\n'
         return txt
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."""
 
-- 
2.46.0