Merge pull request #4 from benjaminkrenn/master

add modified saintelague, add israel example

apportionment.py

@@ -12,6 +12,7 @@ def method(method, votes, seats, parties=string.ascii_letters,
     elif method in ["lrm", "hamilton", "largest_remainder"]:
         return largest_remainder(filtered_votes, seats, parties, verbose)
     elif method in ["dhondt", "jefferson", "saintelague", "webster",
+                    "modified_saintelague",
                     "huntington", "hill", "adams", "dean",
                     "smallestdivisor", "harmonicmean", "equalproportions",
                     "majorfractions", "greatestdivisors"]:
@@ -115,6 +116,10 @@ def divisor(votes, seats, method, parties=string.ascii_letters,
         if verbose:
             print("\nSainte Lague (Webster) method")
         divisors = [2*i+1 for i in range(seats)]
+    elif method in ["modified_saintelague"]:
+        if verbose:
+            print("\nModified Sainte Lague (Webster) method")
+        divisors = [1.4] + [2*i+1 for i in range(1,seats)]
     elif method in ["huntington", "hill", "equalproportions"]:
         if verbose:
             print("\nHuntington-Hill method")
@@ -137,7 +142,7 @@ def divisor(votes, seats, method, parties=string.ascii_letters,
             divisors = [i+1 for i in range(seats)]
     elif method in ["dean", "harmonicmean"]:
         if verbose:
-            print("\Dean method")
+            print("\nDean method")
         if seats < len(votes):
             representatives = __divzero_fewerseatsthanparties(votes,
                                                               seats, parties,
@@ -153,7 +158,7 @@ def divisor(votes, seats, method, parties=string.ascii_letters,
     if seats > sum(representatives):
         weights = []
         for p in votes:
-            if method in ["huntington", "hill"]:
+            if method in ["huntington", "hill", "modified_saintelague"]:
                 weights.append([(p / div) for div in divisors])
             else:
                 weights.append([Fraction(p, div) for div in divisors])

examples/israel_examples.py

@@ -0,0 +1,20 @@
+from __future__ import print_function
+import sys
+sys.path.insert(0, '..')
+import apportionment
+
+with open("./knesset.txt", "r") as f:
+
+    for line in f:
+        knesset_nr, partynames, votes, officialresult, threshold = \
+            eval(line)
+        print("Knesset #" + str(knesset_nr) + ":")
+        result = apportionment.method("dhondt", votes,
+                                      sum(officialresult),
+                                      parties=partynames,
+                                      threshold=None,  # is already excluded from input
+                                      verbose=True)
+        # actual results
+        print("Identical with official result: "
+              + (str(tuple(result) == tuple(officialresult)))
+              + "\n\n")

examples/knesset.txt

@@ -0,0 +1,4 @@
+[19, ['Likud Yisrael Beitenu+Habayit Hayehudi', 'Yesh Atid+Israel Labor Party', 'Shas+United Torah Judaism', 'Hatenua+Meretz', 'United Arab List',  'Hadash+National Democratic Assembly - Balad', 'Kadima'], [885163+345985, 543458+432118, 331868+195892, 189167+172403, 138450, 113439+97030, 78974], [31+12, 19+15, 11+7, 6+6, 4, 4+3, 2], 0.02]
+[20, ['Likud Chaired by Benjamin Netanyahu for Prime Minister+Habayit Hayehudi Chaired by Naftali Bennett', "Zionist Camp Chaired by Isaac Herzog and Tzipi Livni+Israel's Left", 'Joint List (Hadash, National Democratic Assembly, Arab Movement for Renewal, United Arab List)', 'Yesh Atid Chaired by Yair Lapid', 'Kulanu Chaired by Moshe Kahlon+Yisrael Beitenu Chaired by Avigdor Liberman', 'Shas+United Torah Judaism'], [985408+283910, 786313+165529, 446583, 371602, 315360+214906, 241613+210143], [30+8, 24+5, 13, 11, 10+6, 7+6], 0.0325]
+[21, ['Likud Chaired by Benjamin Netanyahu for Prime Minister+United Right', 'Blue and White', 'Shas+United Torah Judaism', "Hadash-Ta'al+Ra'am-Balad", 'Israeli Labor Party+Meretz', 'Yisrael Beitenu', 'Kulanu Chaired by Moshe Kahlon'], [1140370+159468, 1125881, 258275+249049, 193442+143666, 190870+156473, 173004, 152756], [35+5, 35, 8+8, 6+4, 6+4, 5, 4], 0.0325]
+[22, ['Blue and White+Yisrael Beitenu', 'Likud+Yemina', 'Joint List (Hadash, Ra\xe2\x80\x99am, Ta\xe2\x80\x99al, Balad)', 'Shas+United Torah Judaism', 'Labor-Gesher+Democratic Union'], [1151214+310154, 1113617+260655, 470211, 330199+268775, 212782+192495], [33+8, 32+7, 13, 9+7, 6+5], 0.0325]

unittests.py

@@ -7,8 +7,8 @@ import unittest
 import apportionment
 
 
-METHODS = ["quota", "largest_remainder", "dhondt",
-           "saintelague", "huntington", "adams", "dean"]
+METHODS = ["quota", "largest_remainder", "dhondt", "saintelague",
+           "modified_saintelague", "huntington", "adams", "dean"]
 
 
 class TestApprovalMultiwinner(unittest.TestCase):
@@ -19,7 +19,7 @@ class TestApprovalMultiwinner(unittest.TestCase):
                              "huntington", "hill", "adams", "dean",
                              "smallestdivisor", "harmonicmean",
                              "equalproportions", "majorfractions",
-                             "greatestdivisors"]
+                             "greatestdivisors", "modified_saintelague"]
 
         votes = [1]
         seats = 1
@@ -73,6 +73,7 @@ class TestApprovalMultiwinner(unittest.TestCase):
                    "largest_remainder": [51, 44, 2, 2, 1],
                    "dhondt": [52, 45, 1, 1, 1],
                    "saintelague": [51, 43, 2, 2, 2],
+                   "modified_saintelague":  [51, 43, 2, 2, 2],
                    "huntington": [51, 43, 2, 2, 2],
                    "adams": [51, 43, 2, 2, 2],
                    "dean": [51, 43, 2, 2, 2]
@@ -109,6 +110,41 @@ class TestApprovalMultiwinner(unittest.TestCase):
         self.assertFalse(apportionment.within_quota(votes, representatives,
                                                     verbose=False))
 
+    def test_threshold(self):
+        votes = [41, 56, 3]
+        seats = 60
+        threshold = 0.03
+        filtered_votes = apportionment.apply_threshold(votes, threshold)
+        self.assertEqual(filtered_votes, [41, 56, 3],
+                         "Threshold cut too much.")
+        threshold = 0.031
+        filtered_votes = apportionment.apply_threshold(votes, threshold)
+        self.assertEqual(filtered_votes, [41, 56, 0],
+                         "Threshold was not applied correctly.")
+
+        method = "dhondt"
+        threshold = 0
+        unfiltered_result = apportionment.method(method, votes, seats,
+                                                 threshold=threshold,
+                                                 verbose=False)
+        threshold = 0.04
+        filtered_result = apportionment.method(method, votes, seats,
+                                               threshold=threshold,
+                                               verbose=False)
+        self.assertNotEqual(unfiltered_result, filtered_result,
+                            "Result did not change despite threshold")
+
+    def test_saintelague_difference(self):
+        votes = [6, 1]
+        seats = 4
+        r1 = apportionment.method("saintelague", votes,
+                                  seats, verbose=False)  # [4, 0]
+        r2 =  apportionment.method("modified_saintelague", votes,
+                                   seats, verbose=False)  # [3, 1]
+        self.assertNotEqual(r1, r2,
+                            "Saintelague should produce different "+
+                            "result than modified variant.")
+
 
 if __name__ == '__main__':
     unittest.main()