Create voting_puisne.py

voting_puisne.py

@@ -0,0 +1,140 @@
+positions = 3
+verbose = True
+verbosier = True
+nominees = 7
+epsilon = 0 # 1e-6
+
+ballots = [
+    ["Orange", "Pear"],
+    ["Orange", "Pear"],
+    ["Orange", "Pear"],
+
+    ["Pear", "Strawberry", "Cake"],
+    ["Pear", "Strawberry", "Cake"],
+    ["Pear", "Strawberry", "Cake"],
+    ["Pear", "Strawberry", "Cake"],
+    ["Pear", "Strawberry", "Cake"],
+    ["Pear", "Strawberry", "Cake"],
+    ["Pear", "Strawberry", "Cake"],
+    ["Pear", "Strawberry", "Cake"],
+
+    ["Strawberry", "Orange", "Pear"],
+
+    ["Cake", "Chocolate"],
+    ["Cake", "Chocolate"],
+    ["Cake", "Chocolate"],
+
+    ["Chocolate", "Cake", "Burger"],
+
+    ["Burger", "Chicken"],
+    ["Burger", "Chicken"],
+    ["Burger", "Chicken"],
+    ["Burger", "Chicken"],
+
+    ["Chicken", "Chocolate", "Burger"],
+    ["Chicken", "Chocolate", "Burger"],
+    ["Chicken", "Chocolate", "Burger"]
+]
+
+duplicate = []
+for b in ballots:
+    if len(b) != len(set(b)):
+        duplicate.append(str(b))
+if duplicate:
+    print("Ballots with Duplicate Entries:\n  " + "\n  ".join(duplicate) + "\n")
+
+candidates = set(i for j in ballots for i in j)
+print(f"{len(candidates)} Candidates: {', '.join(sorted(candidates))}")
+assert nominees == len(candidates)
+print(f"{len(ballots)} Ballots")
+print(f"{positions} Positions")
+quota = len(ballots)/(positions + 1) + epsilon
+print(f"Quota: {quota}")
+
+elected = set()
+eliminated = set()
+tallies = [{'weight': 1.0, 'order': i} for i in ballots]
+stage = 0
+
+while len(elected) + len(candidates) > positions and len(elected) != positions:
+    assert len(elected) + len(candidates) + len(eliminated) == nominees
+    stage += 1
+    if verbose:
+        print(f"\nRound {stage}")
+
+    # assign each vote to a candidate
+    assignments = {c: [] for c in candidates}
+    while tallies:
+        vote = tallies.pop()
+        # remove any elected or eliminated candidates
+        vote["order"] = [i for i in vote["order"] if i in candidates]
+        if vote['order']:
+            assignments[vote['order'][0]].append(vote)
+
+    kill = True
+    minimum = quota
+    dying = set()
+    progress = {}
+
+    # for each candidate, count up the number of votes
+    # sorting so that candidates are shown elected in the right order (if verbose)
+    for c in sorted(assignments.keys(), key=lambda x: (-sum(v['weight'] for v in assignments[x]), x)):
+        score = sum(v['weight'] for v in assignments[c])
+        progress[c] = score
+
+        # if they score above quota, then elect them and return votes with reevaluated votes
+        if score >= quota:
+            kill = False
+            elected.add(c)
+            candidates.remove(c)
+            if verbose:
+                print(f"  Elected: {c}")
+            for vote in assignments[c]:
+                vote['weight'] *= 1 - quota/score
+                tallies.append(vote)
+        # if they don't score above quota, return votes to the tallies unchanged
+        else:
+            tallies.extend(assignments[c])
+
+        # find the candidates with the minimum scores
+        if score < minimum:
+            dying = set([c])
+            minimum = score
+        elif score == minimum:
+            dying.add(c)
+
+    if verbose and verbosier:
+        print("  " + "; ".join(f"{p}: {progress[p]:.2f}" for p in sorted(progress, key=progress.get, reverse=True)))
+
+    # if someone was elected, move directly to the next round
+    if not kill: continue
+
+    # if eliminating candidates would leave insufficient remaining candidates, announce
+    if len(elected) + len(candidates) - len(dying) < positions:
+        print("Tie In Final Round")
+        print("  " + "\n  ".join(dying))
+        eliminated.update(dying)
+        candidates.difference_update(dying)
+        break
+
+    # eliminate candidates
+    if verbose:
+        print("\n".join(f"  Eliminated: {c}" for c in dying))
+    eliminated.update(dying)
+    candidates.difference_update(dying)
+
+# if candidates remain (who didn't score above quota)
+if candidates:
+    if len(elected) != positions:
+        elected.update(candidates)
+        if verbose:
+            print("\n" + "\n".join(f"Remainder: {c}" for c in candidates))
+    else:
+        eliminated.update(candidates)
+        if verbose:
+            print("\n" + "\n".join(f"Removed: {c}" for c in candidates))
+
+# announce winners
+print("\nWinners:\n  " + "\n  ".join(sorted(elected)))
+if len(elected) < positions:
+    print("\n".join((positions - len(elected)) * ["  + Undetermined"]))