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Merge pull request #7 from frigorific44/master 

Speed Improvement by Using Numpy
master
Martin Lackner 2022-02-16 13:53:06 +01:00 zatwierdzone przez GitHub
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142
apportionment/methods.py
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@ -2,9 +2,10 @@
from __future__ import print_function, division
import string
import math
from fractions import Fraction
import math
import numpy as np
import string
METHODS = [
@ -27,16 +28,17 @@ def compute(
method,
votes,
seats,
fractions=True,
parties=string.ascii_letters,
threshold=None,
tiesallowed=True,
verbose=True,
verbose=True
):
filtered_votes = apply_threshold(votes, threshold)
if method == "quota":
return quota(filtered_votes, seats, parties, tiesallowed, verbose)
return quota(filtered_votes, seats, fractions, parties, tiesallowed, verbose)
elif method in ["lrm", "hamilton", "largest_remainder"]:
return largest_remainder(filtered_votes, seats, parties, tiesallowed, verbose)
return largest_remainder(filtered_votes, seats, fractions, parties, tiesallowed, verbose)
elif method in [
"dhondt",
"jefferson",
@ -53,7 +55,7 @@ def compute(
"majorfractions",
"greatestdivisors",
]:
return divisor(filtered_votes, seats, method, parties, tiesallowed, verbose)
return divisor(filtered_votes, seats, method, fractions, parties, tiesallowed, verbose)
else:
raise NotImplementedError("apportionment method " + method + " not known")
@ -118,33 +120,39 @@ def within_quota(votes, representatives, parties=string.ascii_letters, verbose=T
# Largest remainder method (Hamilton method)
def largest_remainder(
votes, seats, parties=string.ascii_letters, tiesallowed=True, verbose=True
votes, seats, fractions=True, parties=string.ascii_letters, tiesallowed=True, verbose=True
):
# votes = np.array(votes)
if verbose:
print("\nLargest remainder method with Hare quota (Hamilton)")
q = Fraction(sum(votes), seats)
quotas = [Fraction(p, q) for p in votes]
representatives = [int(qu.numerator) // int(qu.denominator) for qu in quotas]
if fractions:
q = Fraction(int(sum(votes)), seats)
quotas = [Fraction(int(p), q) for p in votes]
representatives = np.array([int(qu.numerator // qu.denominator) for qu in quotas])
else:
quotas = (votes * seats) / np.sum(votes)
representatives = np.int_(np.trunc(quotas))
ties = False
if sum(representatives) < seats:
remainders = [a - b for a, b in zip(quotas, representatives)]
cutoff = sorted(remainders, reverse=True)[seats - sum(representatives) - 1]
if np.sum(representatives) < seats:
remainders = quotas - representatives
cutoff = remainders[np.argsort(remainders)[np.sum(representatives) - seats]]
tiebreaking_message = (
" tiebreaking in order of: "
+ str(parties[: len(votes)])
+ "\n ties broken in favor of: "
)
for i in range(len(votes)):
if sum(representatives) == seats and remainders[i] >= cutoff:
reps_sum = np.sum(representatives)
if reps_sum == seats and remainders[i] >= cutoff:
if not ties:
tiebreaking_message = tiebreaking_message[:-2]
tiebreaking_message += "\n to the disadvantage of: "
ties = True
tiebreaking_message += parties[i] + ", "
elif sum(representatives) < seats and remainders[i] > cutoff:
elif reps_sum < seats and remainders[i] > cutoff:
representatives[i] += 1
elif sum(representatives) < seats and remainders[i] == cutoff:
elif reps_sum < seats and remainders[i] == cutoff:
tiebreaking_message += parties[i] + ", "
representatives[i] += 1
if ties and verbose:
@ -156,26 +164,27 @@ def largest_remainder(
if verbose:
__print_results(representatives, parties)
return representatives
return representatives.tolist()
# Divisor methods
def divisor(
votes, seats, method, parties=string.ascii_letters, tiesallowed=True, verbose=True
votes, seats, method, fractions=True, parties=string.ascii_letters, tiesallowed=True, verbose=True
):
representatives = [0] * len(votes)
votes = np.array(votes)
representatives = np.zeros(len(votes), dtype=int)
if method in ["dhondt", "jefferson", "greatestdivisors"]:
if verbose:
print("\nD'Hondt (Jefferson) method")
divisors = [i + 1 for i in range(seats)]
divisors = np.arange(seats) + 1
elif method in ["saintelague", "webster", "majorfractions"]:
if verbose:
print("\nSainte Lague (Webster) method")
divisors = [2 * i + 1 for i in range(seats)]
divisors = 2 * np.arange(seats) + 1
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)]
divisors = np.insert(2 * np.arange(1.0, seats) + 1, 0, 1.4)
elif method in ["huntington", "hill", "equalproportions"]:
if verbose:
print("\nHuntington-Hill method")
@ -184,8 +193,9 @@ def divisor(
votes, seats, parties, tiesallowed, verbose
)
else:
representatives = [1 if p > 0 else 0 for p in votes]
divisors = [math.sqrt((i + 1) * (i + 2)) for i in range(seats)]
representatives = np.where(votes > 0, 1, 0)
divisors = np.arange(seats)
divisors = np.sqrt((divisors + 1) * (divisors + 2))
elif method in ["adams", "smallestdivisor"]:
if verbose:
print("\nAdams method")
@ -194,8 +204,8 @@ def divisor(
votes, seats, parties, tiesallowed, verbose
)
else:
representatives = [1 if p > 0 else 0 for p in votes]
divisors = [i + 1 for i in range(seats)]
representatives = np.where(votes > 0, 1, 0)
divisors = np.arange(seats) + 1
elif method in ["dean", "harmonicmean"]:
if verbose:
print("\nDean method")
@ -204,37 +214,38 @@ def divisor(
votes, seats, parties, tiesallowed, verbose
)
else:
representatives = [1 if p > 0 else 0 for p in votes]
divisors = [
Fraction(2 * (i + 1) * (i + 2), 2 * (i + 1) + 1) for i in range(seats)
]
representatives = np.array([1 if p > 0 else 0 for p in votes])
if fractions:
divisors = np.array([
Fraction(2 * (i + 1) * (i + 2), 2 * (i + 1) + 1) for i in range(seats)
])
else:
divisors = np.arange(seats)
divisors = (2 * (divisors + 1) * (divisors + 2)) / (2 * (divisors + 1) + 1)
else:
raise NotImplementedError("divisor method " + method + " not known")
# assigning representatives
if seats > sum(representatives):
weights = []
for p in votes:
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])
flatweights = sorted([w for l in weights for w in l], reverse=True)
minweight = flatweights[seats - sum(representatives) - 1]
if seats > np.sum(representatives):
if fractions and method not in ["huntington", "hill", "modified_saintelague"]:
weights = np.array([[Fraction(int(p), d) for d in divisors.tolist()] for p in votes])
flatweights = sorted([w for l in weights for w in l])
else:
weights = np.array([p / divisors for p in votes])
flatweights = np.sort(weights, axis=None)
minweight = flatweights[-seats + np.sum(representatives)]
for i in range(len(votes)):
representatives[i] += len([w for w in weights[i] if w > minweight])
representatives += np.count_nonzero(weights > minweight, axis=1)
ties = False
# dealing with ties
if seats > sum(representatives):
if seats > np.sum(representatives):
tiebreaking_message = (
" tiebreaking in order of: "
+ str(parties[: len(votes)])
+ "\n ties broken in favor of: "
)
for i in range(len(votes)):
if sum(representatives) == seats and minweight in weights[i]:
if np.sum(representatives) == seats and minweight in weights[i]:
if not ties:
if not tiesallowed:
raise TiesException("Tie occurred")
@ -242,7 +253,7 @@ def divisor(
tiebreaking_message += "\n to the disadvantage of: "
ties = True
tiebreaking_message += parties[i] + ", "
if sum(representatives) < seats and minweight in weights[i]:
if np.sum(representatives) < seats and minweight in weights[i]:
tiebreaking_message += parties[i] + ", "
representatives[i] += 1
if ties and verbose:
@ -254,12 +265,12 @@ def divisor(
if verbose:
__print_results(representatives, parties)
return representatives
return representatives.tolist()
# required for methods with 0 divisors (Adams, Huntington-Hill)
def __divzero_fewerseatsthanparties(votes, seats, parties, tiesallowed, verbose):
representatives = [0] * len(votes)
representatives = np.zeros(len(votes), dtype=int)
if verbose:
print(
" fewer seats than parties; "
@ -268,13 +279,13 @@ def __divzero_fewerseatsthanparties(votes, seats, parties, tiesallowed, verbose)
)
tiebreaking_message = " ties broken in favor of: "
ties = False
mincount = sorted(votes, reverse=True)[seats - 1]
mincount = np.sort(votes)[-seats]
for i in range(len(votes)):
if sum(representatives) < seats and votes[i] >= mincount:
if np.sum(representatives) < seats and votes[i] >= mincount:
if votes[i] == mincount:
tiebreaking_message += parties[i] + ", "
representatives[i] = 1
elif sum(representatives) == seats and votes[i] >= mincount:
elif np.sum(representatives) == seats and votes[i] >= mincount:
if not ties:
tiebreaking_message = tiebreaking_message[:-2]
tiebreaking_message += "\n to the disadvantage of: "
@ -287,7 +298,7 @@ def __divzero_fewerseatsthanparties(votes, seats, parties, tiesallowed, verbose)
return representatives
def quota(votes, seats, parties=string.ascii_letters, tiesallowed=True, verbose=True):
def quota(votes, seats, fractions=True, parties=string.ascii_letters, tiesallowed=True, verbose=True):
"""The quota method
see Balinski, M. L., & Young, H. P. (1975).
The quota method of apportionment.
@ -301,18 +312,21 @@ def quota(votes, seats, parties=string.ascii_letters, tiesallowed=True, verbose=
)
if verbose:
print("\nQuota method")
representatives = [0] * len(votes)
while sum(representatives) < seats:
quotas = [Fraction(votes[i], representatives[i] + 1) for i in range(len(votes))]
# check if upper quota is violated
for i in range(len(votes)):
upperquota = int(
math.ceil(float(votes[i]) * (sum(representatives) + 1) / sum(votes))
)
if representatives[i] >= upperquota:
quotas[i] = 0
maxquotas = [i for i in range(len(votes)) if quotas[i] == max(quotas)]
votes = np.array(votes)
representatives = np.zeros(len(votes), dtype=int)
while np.sum(representatives) < seats:
if fractions:
quotas = [Fraction(int(votes[i]), int(representatives[i]) + 1)
for i in range(len(votes))]
else:
quotas = votes / (representatives + 1)
# check if upper quota is violated
upperquota = votes * (np.sum(representatives) + 1) / np.sum(votes)
upperquota = np.trunc(np.ceil(upperquota))
quotas = np.where(representatives >= upperquota, 0, quotas)
maxquotas = np.nonzero(quotas == quotas.max())[0]
nextrep = maxquotas[0]
@ -320,7 +334,7 @@ def quota(votes, seats, parties=string.ascii_letters, tiesallowed=True, verbose=
if verbose and len(maxquotas) > 1:
print(
"tiebreaking necessary in round "
+ str(sum(representatives) + 1)
+ str(np.sum(representatives) + 1)
+ ":"
+ " tiebreaking in order of: "
+ str(parties[: len(votes)])
@ -335,4 +349,4 @@ def quota(votes, seats, parties=string.ascii_letters, tiesallowed=True, verbose=
if verbose:
__print_results(representatives, parties)
return representatives
return representatives.tolist()