rjt's Week 276 solutions and blog

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+#!/usr/bin/env python3
+#
+# ch-2.py - Maximum Frequency
+#
+# 2024 Ryan Thompson <rjt@cpan.org>
+
+# First identify which number(s) appear most often in the list,
+# then return the count of all such numbers. Ex. 1, 2, 2, 4, 1, 5
+# should return 4, because the matching numbers are 1,1,2,2 (freq:2)
+def max_freq(ints):
+    # Annoying special case for empty list
+    if len(ints) == 0:
+        return(0)
+
+    # Build the frequency table (freq[n] = # of times n is in ints)
+    freq = {} 
+    for n in ints: freq[n] = freq.setdefault(n,0) + 1
+
+    max_freq = max(freq.values()) # Maximal frequency
+
+    return(sum(filter(lambda x: x == max_freq, freq.values())))
+
+# Examples
+print(max_freq([1, 2, 2, 4, 1, 5]))                  # 4
+print(max_freq([1, 2, 3, 4, 5]))                     # 5
+print(max_freq([1, 2, 2, 4, 6, 1, 5, 6]))            # 6
+print(max_freq(['a', 'a', 'b', 'a', 'b', 'b', 'c'])) # 6
+print(max_freq([3.1415926]))                         # 1
+print(max_freq([]))                                  # 0