def compress(g: MultiGraph, t: set, compressed_node, mutate=False) -> MultiGraph: if not t: return g if mutate: gx = g else: gx = g.copy() tx = t if compressed_node in tx: tx = t.copy() tx.remove(compressed_node) gx.add_node(compressed_node) for node in tx: for edge in gx.edges(node): if edge[0] == node: node_2 = edge[1] else: node_2 = edge[0] if not (node_2 in t or node_2 == compressed_node): gx.add_edge(compressed_node, node_2) gx.remove_node(node) remove = set() for node in gx.adj[compressed_node]: if len(gx.adj[compressed_node][node]) >= 2: # Using a set to remove to avoid messing up iteration of adj remove.add(node) for node in remove: gx.remove_node(node) return gx
def compress(self, g: MultiGraph, t: set, compressed_node, mutate=False) -> MultiGraph:
if not t:
return g
if mutate:
gx = g
else:
gx = g.copy()
tx = t
if compressed_node in tx:
tx = t.copy()
tx.remove(compressed_node)
gx.add_node(compressed_node)
for node in tx:
for edge in gx.edges(node):
if edge[0] == node:
node_2 = edge[1]
else:
node_2 = edge[0]
if not (node_2 in t or node_2 == compressed_node):
gx.add_edge(compressed_node, node_2)
gx.remove_node(node)
remove = set()
for node in gx.adj[compressed_node]:
if len(gx.adj[compressed_node][node]) >= 2:
# Using a set to remove to avoid messing up iteration of adj
remove.add(node)
for node in remove:
gx.remove_node(node)
return gx
def get_fbvs_max_size(self, g: MultiGraph, k: int) -> set:
# we will run the algorithm 4^k times
n = 4 ** k
for _ in range (1, n):
# pass a copy of g, since we need a fresh copy of g for every run
sol = self._get_fbvs_max_size(g.copy(), k)
if sol is not None:
# we found a fbvs for (g,k), so we can return it right away
return sol
return None
def get_fbvs_max_size(self, g: MultiGraph, k: int) -> set:
# we will run the algorithm 4^k times
n = 4**k
for _ in range(1, n):
# pass a copy of g, since we need a fresh copy of g for every run
sol = self._get_fbvs_max_size(g.copy(), k)
if sol is not None:
# we found a fbvs for (g,k), so we can return it right away
return sol
return None
def mif_main(self, g: MultiGraph, f: set, t) -> set:
if f == g.nodes():
return f
if not f:
g_degree = g.degree()
g_max_degree_node = max(g_degree, key=lambda n: n[1])[0]
if g_degree[g_max_degree_node] <= 1:
return set(g.nodes())
else:
fx = f.copy()
fx.add(g_max_degree_node)
gx = g.copy()
gx.remove_node(g_max_degree_node)
mif_set1 = self.preprocess_1(g, fx, t)
mif_set2 = self.preprocess_1(gx, f, t)
if not mif_set1:
return mif_set2
elif not mif_set2:
return mif_set1
else:
return max(mif_set1, mif_set2, key=len)
# Set t as active vertex
if t is None or t not in f:
t = next(iter(f))
gd_over_3 = None
gd_2 = None
for v in g.neighbors(t):
(gd_v, gn_v) = self.generalized_degree(g, f, t, v)
if gd_v <= 1:
f.add(v)
return self.preprocess_1(g, f, t)
elif gd_v >= 3:
gd_over_3 = v
else:
gd_2 = (v, gn_v)
if gd_over_3 is not None:
# Cannot simply use "if gd_over_3" because v might be 0
fx = f.copy()
fx.add(gd_over_3)
gx = g.copy()
gx.remove_node(gd_over_3)
mif_set1 = self.preprocess_1(g, fx, t)
mif_set2 = self.preprocess_1(gx, f, t)
if not mif_set1:
return mif_set2
elif not mif_set2:
return mif_set1
else:
return max(mif_set1, mif_set2, key=len)
elif gd_2 is not None:
(v, gn) = gd_2
fx1 = f.copy()
fx2 = f.copy()
fx1.add(v)
for n in gn:
fx2.add(n)
gx = g.copy()
gx.remove_node(v)
try:
find_cycle(gx.subgraph(fx2))
mif_set1 = None
except:
mif_set1 = self.preprocess_1(gx, fx2, t)
mif_set2 = self.preprocess_1(g, fx1, t)
if not mif_set1:
return mif_set2
elif not mif_set2:
return mif_set1
else:
return max(mif_set1, mif_set2, key=len)
return None
def graph_minus_slow(g: MultiGraph, w: set) -> MultiGraph: gx = g.copy() gx.remove_nodes_from(w) return gx
def mif_main(g: MultiGraph, f: set, t, k: int) -> set: k_set = k != None new_k1 = new_k2 = None if k_set and k > g.order(): return None if f == g.nodes() or (k_set and k <= 0): return f if (not f): g_degree = g.degree() g_max_degree_node = max(g_degree, key=lambda n: g_degree[n]) if (g_degree[g_max_degree_node] <= 1): return set(g.nodes()) else: fx = f.copy() fx.add(g_max_degree_node) gx = g.copy() gx.remove_node(g_max_degree_node) if k_set: new_k1 = k-1 new_k2 = k mif_set1 = mif_preprocess_1(g, fx, t, new_k1) mif_set2 = mif_preprocess_1(gx, f, t, new_k2) if not mif_set1: return mif_set2 elif not mif_set2: return mif_set1 else: return max(mif_set1, mif_set2, key=len) # Set t as active vertex if t == None or not t in f: t = next(iter(f)) gd_over_3 = None gd_2 = None for v in g.neighbors_iter(t): (gd_v, gn_v) = generalized_degree(g, f, t, v) if gd_v <= 1: f.add(v) if k_set: new_k1 = k-1 return mif_preprocess_1(g, f, t, new_k1) elif gd_v >= 3: gd_over_3 = v else: gd_2 = (v, gn_v) if gd_over_3 != None: # Cannot simply use "if gd_over_3" because v might be 0 fx = f.copy() fx.add(gd_over_3) gx = g.copy() gx.remove_node(gd_over_3) if k_set: new_k1 = k-1 new_k2 = k mif_set1 = mif_preprocess_1(g, fx, t, new_k1) mif_set2 = mif_preprocess_1(gx, f, t, new_k2) if not mif_set1: return mif_set2 elif not mif_set2: return mif_set1 else: return max(mif_set1, mif_set2, key=len) elif gd_2 != None: (v, gn) = gd_2 fx1 = f.copy() fx2 = f.copy() fx1.add(v) for n in gn: fx2.add(n) gx = g.copy() gx.remove_node(v) if k_set: new_k1 = k-2 new_k2 = k-1 try: cyc.find_cycle(gx.subgraph(fx2)) mif_set1 = None except: mif_set1 = mif_preprocess_1(gx, fx2, t, new_k1) mif_set2 = mif_preprocess_1(g, fx1, t, new_k2) if not mif_set1: return mif_set2 elif not mif_set2: return mif_set1 else: return max(mif_set1, mif_set2, key=len) return None
