Inzynierka/Lib/site-packages/scipy/optimize/_shgo_lib/triangulation.py

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2023-06-02 12:51:02 +02:00
import numpy as np
import copy
class Complex:
def __init__(self, dim, func, func_args=(), symmetry=False, bounds=None,
g_cons=None, g_args=()):
self.dim = dim
self.bounds = bounds
self.symmetry = symmetry # TODO: Define the functions to be used
# here in init to avoid if checks
self.gen = 0
self.perm_cycle = 0
# Every cell is stored in a list of its generation,
# e.g., the initial cell is stored in self.H[0]
# 1st get new cells are stored in self.H[1] etc.
# When a cell is subgenerated it is removed from this list
self.H = [] # Storage structure of cells
# Cache of all vertices
self.V = VertexCache(func, func_args, bounds, g_cons, g_args)
# Generate n-cube here:
self.n_cube(dim, symmetry=symmetry)
# TODO: Assign functions to a the complex instead
if symmetry:
self.generation_cycle = 1
# self.centroid = self.C0()[-1].x
# self.C0.centroid = self.centroid
else:
self.add_centroid()
self.H.append([])
self.H[0].append(self.C0)
self.hgr = self.C0.homology_group_rank()
self.hgrd = 0 # Complex group rank differential
# self.hgr = self.C0.hg_n
# Build initial graph
self.graph_map()
self.performance = []
self.performance.append(0)
self.performance.append(0)
def __call__(self):
return self.H
def n_cube(self, dim, symmetry=False, printout=False):
"""
Generate the simplicial triangulation of the N-D hypercube
containing 2**n vertices
"""
origin = list(np.zeros(dim, dtype=int))
self.origin = origin
supremum = list(np.ones(dim, dtype=int))
self.supremum = supremum
# tuple versions for indexing
origintuple = tuple(origin)
supremumtuple = tuple(supremum)
x_parents = [origintuple]
if symmetry:
self.C0 = Simplex(0, 0, 0, self.dim) # Initial cell object
self.C0.add_vertex(self.V[origintuple])
i_s = 0
self.perm_symmetry(i_s, x_parents, origin)
self.C0.add_vertex(self.V[supremumtuple])
else:
self.C0 = Cell(0, 0, origin, supremum) # Initial cell object
self.C0.add_vertex(self.V[origintuple])
self.C0.add_vertex(self.V[supremumtuple])
i_parents = []
self.perm(i_parents, x_parents, origin)
if printout:
print("Initial hyper cube:")
for v in self.C0():
v.print_out()
def perm(self, i_parents, x_parents, xi):
# TODO: Cut out of for if outside linear constraint cutting planes
xi_t = tuple(xi)
# Construct required iterator
iter_range = [x for x in range(self.dim) if x not in i_parents]
for i in iter_range:
i2_parents = copy.copy(i_parents)
i2_parents.append(i)
xi2 = copy.copy(xi)
xi2[i] = 1
# Make new vertex list a hashable tuple
xi2_t = tuple(xi2)
# Append to cell
self.C0.add_vertex(self.V[xi2_t])
# Connect neighbors and vice versa
# Parent point
self.V[xi2_t].connect(self.V[xi_t])
# Connect all family of simplices in parent containers
for x_ip in x_parents:
self.V[xi2_t].connect(self.V[x_ip])
x_parents2 = copy.copy(x_parents)
x_parents2.append(xi_t)
# Permutate
self.perm(i2_parents, x_parents2, xi2)
def perm_symmetry(self, i_s, x_parents, xi):
# TODO: Cut out of for if outside linear constraint cutting planes
xi_t = tuple(xi)
xi2 = copy.copy(xi)
xi2[i_s] = 1
# Make new vertex list a hashable tuple
xi2_t = tuple(xi2)
# Append to cell
self.C0.add_vertex(self.V[xi2_t])
# Connect neighbors and vice versa
# Parent point
self.V[xi2_t].connect(self.V[xi_t])
# Connect all family of simplices in parent containers
for x_ip in x_parents:
self.V[xi2_t].connect(self.V[x_ip])
x_parents2 = copy.copy(x_parents)
x_parents2.append(xi_t)
i_s += 1
if i_s == self.dim:
return
# Permutate
self.perm_symmetry(i_s, x_parents2, xi2)
def add_centroid(self):
"""Split the central edge between the origin and supremum of
a cell and add the new vertex to the complex"""
self.centroid = list(
(np.array(self.origin) + np.array(self.supremum)) / 2.0)
self.C0.add_vertex(self.V[tuple(self.centroid)])
self.C0.centroid = self.centroid
# Disconnect origin and supremum
self.V[tuple(self.origin)].disconnect(self.V[tuple(self.supremum)])
# Connect centroid to all other vertices
for v in self.C0():
self.V[tuple(self.centroid)].connect(self.V[tuple(v.x)])
self.centroid_added = True
return
# Construct incidence array:
def incidence(self):
if self.centroid_added:
self.structure = np.zeros([2 ** self.dim + 1, 2 ** self.dim + 1],
dtype=int)
else:
self.structure = np.zeros([2 ** self.dim, 2 ** self.dim],
dtype=int)
for v in self.HC.C0():
for v2 in v.nn:
self.structure[v.index, v2.index] = 1
return
# A more sparse incidence generator:
def graph_map(self):
""" Make a list of size 2**n + 1 where an entry is a vertex
incidence, each list element contains a list of indexes
corresponding to that entries neighbors"""
self.graph = [[v2.index for v2 in v.nn] for v in self.C0()]
# Graph structure method:
# 0. Capture the indices of the initial cell.
# 1. Generate new origin and supremum scalars based on current generation
# 2. Generate a new set of vertices corresponding to a new
# "origin" and "supremum"
# 3. Connected based on the indices of the previous graph structure
# 4. Disconnect the edges in the original cell
def sub_generate_cell(self, C_i, gen):
"""Subgenerate a cell `C_i` of generation `gen` and
homology group rank `hgr`."""
origin_new = tuple(C_i.centroid)
centroid_index = len(C_i()) - 1
# If not gen append
try:
self.H[gen]
except IndexError:
self.H.append([])
# Generate subcubes using every extreme vertex in C_i as a supremum
# and the centroid of C_i as the origin
H_new = [] # list storing all the new cubes split from C_i
for i, v in enumerate(C_i()[:-1]):
supremum = tuple(v.x)
H_new.append(
self.construct_hypercube(origin_new, supremum, gen, C_i.hg_n))
for i, connections in enumerate(self.graph):
# Present vertex V_new[i]; connect to all connections:
if i == centroid_index: # Break out of centroid
break
for j in connections:
C_i()[i].disconnect(C_i()[j])
# Destroy the old cell
if C_i is not self.C0: # Garbage collector does this anyway; not needed
del C_i
# TODO: Recalculate all the homology group ranks of each cell
return H_new
def split_generation(self):
"""
Run sub_generate_cell for every cell in the current complex self.gen
"""
no_splits = False # USED IN SHGO
try:
for c in self.H[self.gen]:
if self.symmetry:
# self.sub_generate_cell_symmetry(c, self.gen + 1)
self.split_simplex_symmetry(c, self.gen + 1)
else:
self.sub_generate_cell(c, self.gen + 1)
except IndexError:
no_splits = True # USED IN SHGO
self.gen += 1
return no_splits # USED IN SHGO
def construct_hypercube(self, origin, supremum, gen, hgr,
printout=False):
"""
Build a hypercube with triangulations symmetric to C0.
Parameters
----------
origin : vec
supremum : vec (tuple)
gen : generation
hgr : parent homology group rank
"""
# Initiate new cell
v_o = np.array(origin)
v_s = np.array(supremum)
C_new = Cell(gen, hgr, origin, supremum)
C_new.centroid = tuple((v_o + v_s) * .5)
# Build new indexed vertex list
V_new = []
for i, v in enumerate(self.C0()[:-1]):
v_x = np.array(v.x)
sub_cell_t1 = v_o - v_o * v_x
sub_cell_t2 = v_s * v_x
vec = sub_cell_t1 + sub_cell_t2
vec = tuple(vec)
C_new.add_vertex(self.V[vec])
V_new.append(vec)
# Add new centroid
C_new.add_vertex(self.V[C_new.centroid])
V_new.append(C_new.centroid)
# Connect new vertices #TODO: Thread into other loop; no need for V_new
for i, connections in enumerate(self.graph):
# Present vertex V_new[i]; connect to all connections:
for j in connections:
self.V[V_new[i]].connect(self.V[V_new[j]])
if printout:
print("A sub hyper cube with:")
print("origin: {}".format(origin))
print("supremum: {}".format(supremum))
for v in C_new():
v.print_out()
# Append the new cell to the to complex
self.H[gen].append(C_new)
return C_new
def split_simplex_symmetry(self, S, gen):
"""
Split a hypersimplex S into two sub simplices by building a hyperplane
which connects to a new vertex on an edge (the longest edge in
dim = {2, 3}) and every other vertex in the simplex that is not
connected to the edge being split.
This function utilizes the knowledge that the problem is specified
with symmetric constraints
The longest edge is tracked by an ordering of the
vertices in every simplices, the edge between first and second
vertex is the longest edge to be split in the next iteration.
"""
# If not gen append
try:
self.H[gen]
except IndexError:
self.H.append([])
# Find new vertex.
# V_new_x = tuple((np.array(C()[0].x) + np.array(C()[1].x)) / 2.0)
s = S()
firstx = s[0].x
lastx = s[-1].x
V_new = self.V[tuple((np.array(firstx) + np.array(lastx)) / 2.0)]
# Disconnect old longest edge
self.V[firstx].disconnect(self.V[lastx])
# Connect new vertices to all other vertices
for v in s[:]:
v.connect(self.V[V_new.x])
# New "lower" simplex
S_new_l = Simplex(gen, S.hg_n, self.generation_cycle,
self.dim)
S_new_l.add_vertex(s[0])
S_new_l.add_vertex(V_new) # Add new vertex
for v in s[1:-1]: # Add all other vertices
S_new_l.add_vertex(v)
# New "upper" simplex
S_new_u = Simplex(gen, S.hg_n, S.generation_cycle, self.dim)
# First vertex on new long edge
S_new_u.add_vertex(s[S_new_u.generation_cycle + 1])
for v in s[1:-1]: # Remaining vertices
S_new_u.add_vertex(v)
for k, v in enumerate(s[1:-1]): # iterate through inner vertices
if k == S.generation_cycle:
S_new_u.add_vertex(V_new)
else:
S_new_u.add_vertex(v)
S_new_u.add_vertex(s[-1]) # Second vertex on new long edge
self.H[gen].append(S_new_l)
self.H[gen].append(S_new_u)
return
# Plots
def plot_complex(self):
"""
Here, C is the LIST of simplexes S in the
2- or 3-D complex
To plot a single simplex S in a set C, use e.g., [C[0]]
"""
from matplotlib import pyplot
if self.dim == 2:
pyplot.figure()
for C in self.H:
for c in C:
for v in c():
if self.bounds is None:
x_a = np.array(v.x, dtype=float)
else:
x_a = np.array(v.x, dtype=float)
for i in range(len(self.bounds)):
x_a[i] = (x_a[i] * (self.bounds[i][1]
- self.bounds[i][0])
+ self.bounds[i][0])
# logging.info('v.x_a = {}'.format(x_a))
pyplot.plot([x_a[0]], [x_a[1]], 'o')
xlines = []
ylines = []
for vn in v.nn:
if self.bounds is None:
xn_a = np.array(vn.x, dtype=float)
else:
xn_a = np.array(vn.x, dtype=float)
for i in range(len(self.bounds)):
xn_a[i] = (xn_a[i] * (self.bounds[i][1]
- self.bounds[i][0])
+ self.bounds[i][0])
# logging.info('vn.x = {}'.format(vn.x))
xlines.append(xn_a[0])
ylines.append(xn_a[1])
xlines.append(x_a[0])
ylines.append(x_a[1])
pyplot.plot(xlines, ylines)
if self.bounds is None:
pyplot.ylim([-1e-2, 1 + 1e-2])
pyplot.xlim([-1e-2, 1 + 1e-2])
else:
pyplot.ylim(
[self.bounds[1][0] - 1e-2, self.bounds[1][1] + 1e-2])
pyplot.xlim(
[self.bounds[0][0] - 1e-2, self.bounds[0][1] + 1e-2])
pyplot.show()
elif self.dim == 3:
fig = pyplot.figure()
ax = fig.add_subplot(111, projection='3d')
for C in self.H:
for c in C:
for v in c():
x = []
y = []
z = []
# logging.info('v.x = {}'.format(v.x))
x.append(v.x[0])
y.append(v.x[1])
z.append(v.x[2])
for vn in v.nn:
x.append(vn.x[0])
y.append(vn.x[1])
z.append(vn.x[2])
x.append(v.x[0])
y.append(v.x[1])
z.append(v.x[2])
# logging.info('vn.x = {}'.format(vn.x))
ax.plot(x, y, z, label='simplex')
pyplot.show()
else:
print("dimension higher than 3 or wrong complex format")
return
class VertexGroup:
def __init__(self, p_gen, p_hgr):
self.p_gen = p_gen # parent generation
self.p_hgr = p_hgr # parent homology group rank
self.hg_n = None
self.hg_d = None
# Maybe add parent homology group rank total history
# This is the sum off all previously split cells
# cumulatively throughout its entire history
self.C = []
def __call__(self):
return self.C
def add_vertex(self, V):
if V not in self.C:
self.C.append(V)
def homology_group_rank(self):
"""
Returns the homology group order of the current cell
"""
if self.hg_n is None:
self.hg_n = sum(1 for v in self.C if v.minimiser())
return self.hg_n
def homology_group_differential(self):
"""
Returns the difference between the current homology group of the
cell and its parent group
"""
if self.hg_d is None:
self.hgd = self.hg_n - self.p_hgr
return self.hgd
def polytopial_sperner_lemma(self):
"""
Returns the number of stationary points theoretically contained in the
cell based information currently known about the cell
"""
pass
def print_out(self):
"""
Print the current cell to console
"""
for v in self():
v.print_out()
class Cell(VertexGroup):
"""
Contains a cell that is symmetric to the initial hypercube triangulation
"""
def __init__(self, p_gen, p_hgr, origin, supremum):
super().__init__(p_gen, p_hgr)
self.origin = origin
self.supremum = supremum
self.centroid = None # (Not always used)
# TODO: self.bounds
class Simplex(VertexGroup):
"""
Contains a simplex that is symmetric to the initial symmetry constrained
hypersimplex triangulation
"""
def __init__(self, p_gen, p_hgr, generation_cycle, dim):
super().__init__(p_gen, p_hgr)
self.generation_cycle = (generation_cycle + 1) % (dim - 1)
class Vertex:
def __init__(self, x, bounds=None, func=None, func_args=(), g_cons=None,
g_cons_args=(), nn=None, index=None):
self.x = x
self.order = sum(x)
x_a = np.array(x, dtype=float)
if bounds is not None:
for i, (lb, ub) in enumerate(bounds):
x_a[i] = x_a[i] * (ub - lb) + lb
# TODO: Make saving the array structure optional
self.x_a = x_a
# Note Vertex is only initiated once for all x so only
# evaluated once
if func is not None:
self.feasible = True
if g_cons is not None:
for g, args in zip(g_cons, g_cons_args):
if g(self.x_a, *args) < 0.0:
self.f = np.inf
self.feasible = False
break
if self.feasible:
self.f = func(x_a, *func_args)
if nn is not None:
self.nn = nn
else:
self.nn = set()
self.fval = None
self.check_min = True
# Index:
if index is not None:
self.index = index
def __hash__(self):
return hash(self.x)
def connect(self, v):
if v is not self and v not in self.nn:
self.nn.add(v)
v.nn.add(self)
if self.minimiser():
v._min = False
v.check_min = False
# TEMPORARY
self.check_min = True
v.check_min = True
def disconnect(self, v):
if v in self.nn:
self.nn.remove(v)
v.nn.remove(self)
self.check_min = True
v.check_min = True
def minimiser(self):
"""Check whether this vertex is strictly less than all its neighbors"""
if self.check_min:
self._min = all(self.f < v.f for v in self.nn)
self.check_min = False
return self._min
def print_out(self):
print("Vertex: {}".format(self.x))
constr = 'Connections: '
for vc in self.nn:
constr += '{} '.format(vc.x)
print(constr)
print('Order = {}'.format(self.order))
class VertexCache:
def __init__(self, func, func_args=(), bounds=None, g_cons=None,
g_cons_args=(), indexed=True):
self.cache = {}
self.func = func
self.g_cons = g_cons
self.g_cons_args = g_cons_args
self.func_args = func_args
self.bounds = bounds
self.nfev = 0
self.size = 0
if indexed:
self.index = -1
def __getitem__(self, x, indexed=True):
try:
return self.cache[x]
except KeyError:
if indexed:
self.index += 1
xval = Vertex(x, bounds=self.bounds,
func=self.func, func_args=self.func_args,
g_cons=self.g_cons,
g_cons_args=self.g_cons_args,
index=self.index)
else:
xval = Vertex(x, bounds=self.bounds,
func=self.func, func_args=self.func_args,
g_cons=self.g_cons,
g_cons_args=self.g_cons_args)
# logging.info("New generated vertex at x = {}".format(x))
# NOTE: Surprisingly high performance increase if logging is commented out
self.cache[x] = xval
# TODO: Check
if self.func is not None:
if self.g_cons is not None:
if xval.feasible:
self.nfev += 1
self.size += 1
else:
self.size += 1
else:
self.nfev += 1
self.size += 1
return self.cache[x]