def jacobi(a_matrix: sp.csr_matrix, residual: np.array) -> np.array:
"""Return vector(np.matrix) obtained by multiplication of inverted a_matrix argument diagonal by residual vector."""
_to_return = {} # type: dict
if 'inverted' not in _to_return:
# we want to calculate matrix inversion only once...
_to_return['inverted'] = 1.0 / (a_matrix.diagonal(0) + 1e-6)
return _to_return['inverted'] * residual
def is_bipartite(adjacency: sparse.csr_matrix, return_biadjacency: bool = False) \
-> Union[bool, Tuple[bool, Optional[sparse.csr_matrix], Optional[np.ndarray], Optional[np.ndarray]]]:
"""Check whether an undirected graph is bipartite.
* Graphs
Parameters
----------
adjacency :
Adjacency matrix of the graph (symmetric).
return_biadjacency :
If ``True``, return a biadjacency matrix of the graph if bipartite.
Returns
-------
is_bipartite : bool
A boolean denoting if the graph is bipartite.
biadjacency : sparse.csr_matrix
A biadjacency matrix of the graph if bipartite (optional).
rows : np.ndarray
Index of rows in the original graph (optional).
cols : np.ndarray
Index of columns in the original graph (optional).
"""
if not is_symmetric(adjacency):
raise ValueError('The graph must be undirected.')
if adjacency.diagonal().any():
if return_biadjacency:
return False, None, None, None
else:
return False
n = adjacency.indptr.shape[0] - 1
coloring = np.full(n, -1, dtype=int)
exists_remaining = n
while exists_remaining:
src = np.argwhere(coloring == -1)[0, 0]
next_nodes = [src]
coloring[src] = 0
exists_remaining -= 1
while next_nodes:
node = next_nodes.pop()
for neighbor in adjacency.indices[adjacency.indptr[node]:adjacency.
indptr[node + 1]]:
if coloring[neighbor] == -1:
coloring[neighbor] = 1 - coloring[node]
next_nodes.append(neighbor)
exists_remaining -= 1
elif coloring[neighbor] == coloring[node]:
if return_biadjacency:
return False, None, None, None
else:
return False
if return_biadjacency:
rows = np.argwhere(coloring == 0).ravel()
cols = np.argwhere(coloring == 1).ravel()
return True, adjacency[rows, :][:, cols], rows, cols
else:
return True
def is_bipartite(
adjacency: sparse.csr_matrix,
return_biadjacency: bool = False
) -> Union[bool, Tuple[bool, Optional[sparse.csr_matrix]]]:
"""Check whether an undirected graph is bipartite and can return a possible biadjacency.
Parameters
----------
adjacency:
The symmetric adjacency matrix of the graph.
return_biadjacency:
If ``True`` , a possible biadjacency is returned if the graph is bipartite (None is returned otherwise)
Returns
-------
is_bipartite: bool
A boolean denoting if the graph is bipartite
biadjacency: sparse.csr_matrix
A possible biadjacency of the bipartite graph (None if the graph is not bipartite)
"""
if not is_symmetric(adjacency):
raise ValueError('The graph must be undirected.')
if adjacency.diagonal().any():
if return_biadjacency:
return False, None
else:
return False
n_nodes = adjacency.indptr.shape[0] - 1
coloring = np.full(n_nodes, -1, dtype=int)
exists_remaining = n_nodes
while exists_remaining:
src = np.argwhere(coloring == -1)[0, 0]
next_nodes = [src]
coloring[src] = 0
exists_remaining -= 1
while next_nodes:
node = next_nodes.pop()
for neighbor in adjacency.indices[adjacency.indptr[node]:adjacency.
indptr[node + 1]]:
if coloring[neighbor] == -1:
coloring[neighbor] = 1 - coloring[node]
next_nodes.append(neighbor)
exists_remaining -= 1
elif coloring[neighbor] == coloring[node]:
if return_biadjacency:
return False, None
else:
return False
if return_biadjacency:
return True, adjacency[coloring == 0, :][:, coloring == 1]
else:
return True
def distanceNormalize(pSparseCsrMatrix: sparse.csr_matrix, pWindowSize_bins: int):
#compute the means along the diagonals (= same distance)
#and divide all values on the diagonals by their respective mean
diagList = []
winsize = min(pSparseCsrMatrix.shape[0], pWindowSize_bins)
winsize = max(winsize, 0) #ensure positivity
for i in range(-winsize+1, winsize):
diagArr = pSparseCsrMatrix.diagonal(i).astype("float32")
meanVal = np.mean(diagArr[diagArr != 0]) #as in Farre et al
diagArr /= meanVal
diagArr[diagArr == 0.0] = 1.0 #as in Farre et al.
diagList.append(diagArr)
distNormalizedMatrix = sparse.diags(diagList,np.arange(-winsize+1, winsize),format="csr")
return distNormalizedMatrix
def _assemble_neumann_common(
self,
g: pp.Grid,
data: Dict,
M: sps.csr_matrix,
mass: sps.csr_matrix,
bc_weight: float = None,
) -> Tuple[sps.csr_matrix, np.ndarray]:
""" Impose Neumann boundary discretization on an already assembled
system matrix.
Common implementation for VEM and RT0. The parameter mass should be
adapted to the discretization method in question
"""
norm = sps.linalg.norm(mass, np.inf) if bc_weight else 1
parameter_dictionary = data[pp.PARAMETERS][self.keyword]
bc = parameter_dictionary["bc"]
# assign the Neumann boundary conditions
# For dual discretizations, internal boundaries
# are handled by assigning Dirichlet conditions. THus, we remove them
# from the is_neu (where they belong by default) and add them in
# is_dir.
is_neu = np.logical_and(bc.is_neu, np.logical_not(bc.is_internal))
if bc and np.any(is_neu):
is_neu = np.hstack((is_neu, np.zeros(g.num_cells, dtype=np.bool)))
is_neu = np.where(is_neu)[0]
# set in an efficient way the essential boundary conditions, by
# clear the rows and put norm in the diagonal
for row in is_neu:
M.data[M.indptr[row]:M.indptr[row + 1]] = 0.0
d = M.diagonal()
d[is_neu] = norm
M.setdiag(d)
return M, norm
def is_acyclic(adjacency: sparse.csr_matrix) -> bool:
"""Check whether a graph has no cycle.
Parameters
----------
adjacency:
Adjacency matrix of the graph.
Returns
-------
is_acyclic : bool
A boolean with value True if the graph has no cycle and False otherwise
"""
n_nodes = adjacency.shape[0]
n_cc = sparse.csgraph.connected_components(adjacency,
(not is_symmetric(adjacency)),
'strong', False)
if n_cc == n_nodes:
# check for self-loops (= cycles)
return (adjacency.diagonal() == 0).all()
else:
return False
def mask_test_edges(adj: sp.csr_matrix):
# Function to build test set with 2% positive links
# Remove diagonal elements
adj = adj - sp.dia_matrix((adj.diagonal()[np.newaxis, :], [0]), shape=adj.shape)
adj.eliminate_zeros()
adj_triu = sp.triu(adj)
adj_tuple = sparse_to_tuple(adj_triu)
edges = adj_tuple[0]
edges_all = sparse_to_tuple(adj)[0]
num_test = int(np.floor(edges.shape[0] / 10.))
num_val = int(np.floor(edges.shape[0] / 10.))
# split to get the training, valid and test set.
all_edge_idx = range(edges.shape[0])
all_edge_idx = list(all_edge_idx)
np.random.shuffle(all_edge_idx)
val_edge_idx = all_edge_idx[:num_val]
test_edge_idx = all_edge_idx[num_val:(num_val + num_test)]
test_edges = edges[test_edge_idx]
val_edges = edges[val_edge_idx]
train_edges = np.delete(edges, np.hstack([test_edge_idx, val_edge_idx]), axis=0)
def ismember(a, b):
rows_close = np.all((a - b[:, None]) == 0, axis=-1)
return np.any(rows_close)
test_edges_false = []
while len(test_edges_false) < len(test_edges):
n_rnd = len(test_edges) - len(test_edges_false)
# num_nodes = adj.shape[0]
rnd = np.random.randint(0, adj.shape[0], size=2 * n_rnd)
idxs_i = rnd[:n_rnd]
idxs_j = rnd[n_rnd:]
for i in range(n_rnd):
idx_i = idxs_i[i]
idx_j = idxs_j[i]
if idx_i == idx_j:
continue
if ismember([idx_i, idx_j], edges_all):
continue
if test_edges_false:
if ismember([idx_j, idx_i], np.array(test_edges_false)):
continue
if ismember([idx_i, idx_j], np.array(test_edges_false)):
continue
test_edges_false.append([idx_i, idx_j])
val_edges_false = []
while len(val_edges_false) < len(val_edges):
n_rnd = len(val_edges) - len(val_edges_false)
rnd = np.random.randint(0, adj.shape[0], size=2 * n_rnd)
idxs_i = rnd[:n_rnd]
idxs_j = rnd[n_rnd:]
for i in range(n_rnd):
idx_i = idxs_i[i]
idx_j = idxs_j[i]
if idx_i == idx_j:
continue
if ismember([idx_i, idx_j], train_edges):
continue
if ismember([idx_j, idx_i], train_edges):
continue
if ismember([idx_i, idx_j], val_edges):
continue
if ismember([idx_j, idx_i], val_edges):
continue
if val_edges_false:
if ismember([idx_j, idx_i], np.array(val_edges_false)):
continue
if ismember([idx_i, idx_j], np.array(val_edges_false)):
continue
val_edges_false.append([idx_i, idx_j])
# Re-build adj matrix
data = np.ones(train_edges.shape[0])
adj_train = sp.csr_matrix((data, (train_edges[:, 0], train_edges[:, 1])), shape=adj.shape)
adj_train = adj_train + adj_train.T
return adj_train, train_edges, val_edges, val_edges_false, test_edges, test_edges_false
