def multi_way_partitioning(items, bin_count):
"""
Greedily divide weighted items equally across bins (multi-way partition problem)
This approximately minimises the difference between the largest and smallest
sum of weights in a bin.
Parameters
----------
items : iterable((item :: any) : (weight :: number))
Weighted items
bin_count : int
Number of bins
Returns
-------
bins : bag(bin :: frozenbag(item :: any))
Bins with the items
References
----------
.. [1] http://stackoverflow.com/a/6855546/1031434 describes the greedy algorithm
.. [2] http://ijcai.org/Proceedings/09/Papers/096.pdf defines the problem and describes algorithms
"""
bins = [_Bin() for _ in range(bin_count)]
for item, weight in sorted(items, key=lambda x: x[1], reverse=True):
bin_ = min(bins, key=lambda bin_: bin_.weights_sum)
bin_.add(item, weight)
return bag(frozenbag(bin_.items) for bin_ in bins)
def __derivative_of_variable(me, w, p):
ww, iww, _, _ = me.__variable_context(w)
pp = ww[w] + frozenbag([p])
if pp in iww:
dwdp = iww[pp]
else:
dwdp = Function(w.function_space())
ww[dwdp] = pp
iww[pp] = dwdp
return dwdp
def test_happy_days(self, items, bin_count, ideal_distance):
'''When any other input, ...'''
bins = multi_way_partitioning(items, bin_count)
# Fill as many bins as possible
assert bins.count(frozenbag()) == max(bin_count - len(items), 0)
# Relative error to ideal solution should be acceptable
actual_distance = self.get_distance(self.reapply_weights(items, bins))
assert actual_distance >= (ideal_distance - 1e8), 'bug in test'
assert actual_distance <= 1.3 * ideal_distance
def __form_derivative_recursive(me, pp, FF, iFF):
if pp in iFF:
dFdpp = iFF[pp]
else:
pp0 = bag(pp)
p = pp0.pop()
pp0 = frozenbag(pp0)
dFdpp0 = me.__form_derivative_recursive(pp0, FF, iFF)
dFdpp = me.__derivative_of_form(dFdpp0, p)
FF[dFdpp] = pp
iFF[pp] = dFdpp
return dFdpp
def __derivative_of_form(me, F, p):
FF, iFF = me.__form_context(F)
pp = FF[F] + frozenbag([p])
if pp in iFF:
dFdp = iFF[pp]
else:
dFdp = derivative(F, me.m, p)
for w in F.coefficients():
if (w in me.uu) or (w in me.vv):
dFdp = dFdp + derivative(F, w, me.__derivative_of_variable(w, p))
FF[dFdp] = pp
iFF[pp] = dFdp
return dFdp
def get_optimal(self):
"""
Restituisce la politica ottimale
Returns
-----------------------------------
(frozenbag) optimal
Politica ottimale appresa
"""
optimal = self.env.get_init_state()
while not self.env.is_terminal_state(optimal):
optimal = frozenbag(
list(optimal) + [self.get_argmax_action(optimal)])
return optimal
def compute_derivative_of_quantity_of_interest(me, derivative_directions_pp, output_direction_z):
pp = frozenbag(derivative_directions_pp)
if output_direction_z is not None:
me.z.vector()[:] = output_direction_z.vector()[:].copy()
me.__check_if_m_changed_and_update_accordingly()
me.__check_if_z_changed_and_update_accordingly()
me.num_changed_p = 0
for p in pp.unique_elements():
me.__check_if_p_changed_and_update_accordingly(p)
# print('me.num_changed_p=', me.num_changed_p)
# me.solved_variables.clear()
if output_direction_z is not None:
F = me.__form_derivative_recursive(pp, me.GG, me.iGG)
else:
F = me.__form_derivative_recursive(pp, me.QQ, me.iQQ)
return me._evaluate_form(F)
def __init__(me, quantity_of_interest_form_Q, state_equation_S, state_bcs,
parameter_m, state_variable_u):
me.Q = quantity_of_interest_form_Q
me.S = state_equation_S
me.m = parameter_m
me.u = state_variable_u
me.uu = {me.u : frozenbag()}
me.iuu = {frozenbag(): me.u}
me.bcs = state_bcs
me.zero_bcs = [DirichletBC(bc) for bc in me.bcs]
for bc in me.zero_bcs:
bc.homogenize()
me.SS = {me.S : frozenbag()}
me.iSS = {frozenbag() : me.S}
me.QQ = {me.Q : frozenbag()}
me.iQQ = {frozenbag() : me.Q}
me.M = me.m.function_space()
me.V = me.u.function_space()
me.Z = me.Q.arguments()[0].function_space()
me.v = Function(me.V) # Adjoint variable
me.z = Function(me.Z)
S2 = replace(me.S, {TestFunction(me.V) : me.v})
Q2 = replace(me.Q, {TestFunction(me.Z) : me.z})
lagrangian = Q2 + S2
me.A = derivative(lagrangian, me.u, TestFunction(me.V)) # Adjoint equation
me.G = derivative(lagrangian, me.m, TestFunction(me.M))
me.vv = {me.v : frozenbag()}
me.ivv = {frozenbag() : me.v}
me.AA = {me.A : frozenbag()}
me.iAA = {frozenbag() : me.A}
me.GG = {me.G : frozenbag()}
me.iGG = {frozenbag() : me.G}
me.solved_variables = set()
me.all_right_hand_sides = dict() # equation -> rhs form
me.__incremental_state_solver, me.__incremental_adjoint_solver = me.__make_solvers()
#
n_hash_vecs = 10
me.__M_hash_vecs = np.random.randn(n_hash_vecs, me.M.dim())
# me.__V_hash_vecs = np.random.randn(n_hash_vecs, me.V.dim())
me.__Z_hash_vecs = np.random.randn(n_hash_vecs, me.Z.dim())
me.__m_hash = me.__compute_function_hash(me.m)
me.__z_hash = me.__compute_function_hash(me.z)
me.__pp_hashes = dict() # derivative direction p -> hash vector
me.__hash_tol = 1e-14
me.num_changed_p = 0
def calc_k(bag): prod = reduce(lambda x,y: x*y, bag, 1) return prod - sum(bag) + len(bag) found_ks = defaultdict(int) FOUND_KS = set() for e,pf in enumerate(prime_fact_upto(N)): if e < 2: continue if e % 100 == 0: print e partitions = partition(trans_pf_dict_to_bag(pf)) bags = set(frozenbag(map(lambda x: reduce(lambda y,z: y*z, x, 1), p)) for p in partitions) for k in map(calc_k, bags): FOUND_KS.add(k) if found_ks[k] == 0: found_ks[k] = e print sum(set((found_ks[i] for i in xrange(2,12001)))) ######################################################################## #dp method? N = 100 K = N/2 # prod_partitions = [[(,)]*K for i in xrange(N)]
def test_one_bin(self):
'''When one bin, return single bin containing all items'''
assert multi_way_partitioning([(1,2), (2,3)], bin_count=1) == bag([frozenbag([1,2])])
def test_one_item(self):
'''When one item, return 1 singleton and x empty bins'''
assert multi_way_partitioning([(1,2)], bin_count=2) == bag([frozenbag([1]), frozenbag()])
def test_no_items(self):
'''When no items, return empty bins'''
assert multi_way_partitioning([], bin_count=2) == bag([frozenbag(), frozenbag()])
