def get_subgraph_nedges(self, rows, cols):
"""
Pulls out an arbitrary i.e. non-contiguous submatrix out of
a sparse.coo_matrix.
Returns
------
tuples of org_row_id, org_col_id, value
"""
matr = self.sm.tocoo()
gr = -1 * st.ones(matr.shape[0], dtype=int)
gc = -1 * st.ones(matr.shape[1], dtype=int)
lr = len(rows)
lc = len(cols)
ar = st.arange(0, lr, 1)
ac = st.arange(0, lc, 1)
gr[rows[ar]] = ar
gc[cols[ac]] = ac
mrow = matr.row
mcol = matr.col
newelem = (gr[mrow] > -1) & (gc[mcol] > -1)
subvalues = matr.data[newelem]
if self.weighted:
nedges = len(subvalues)
else:
nedges = subvalues.sum()
return nedges
def get_sub_graph(self, rows, cols):
cootensor = self.graph_tensor
gr = -1 * st.ones(cootensor.shape[0], dtype=int)
gc = -1 * st.ones(cootensor.shape[1], dtype=int)
lr = len(rows)
lc = len(cols)
ar = st.arange(0, lr, 1)
ac = st.arange(0, lc, 1)
gr[rows[ar]] = ar
gc[cols[ac]] = ac
mrow = cootensor.coords[0]
mcol = cootensor.coords[1]
newelem = (gr[mrow] > -1) & (gc[mcol] > -1)
newrows = mrow[newelem]
newcols = mcol[newelem]
subcoords = st.stack(
(gr[newrows], gc[newcols], *cootensor.coords[2:, newelem]), axis=0)
subvalues = cootensor.data[newelem]
subtensor = st.STensor((subcoords, subvalues),
shape=(lr, lc, *cootensor.shape[2:]))
return st.Graph(subtensor, self.weighted, self.bipartite, self.modet)