Thesis/data/algos.pyx

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2022-12-26 04:54:46 +00:00
# Copyright (c) Microsoft Corporation.
# Licensed under the MIT License.
import cython
from cython.parallel cimport prange, parallel
cimport numpy
import numpy
def floyd_warshall(adjacency_matrix):
(nrows, ncols) = adjacency_matrix.shape
assert nrows == ncols
cdef unsigned int n = nrows
adj_mat_copy = adjacency_matrix.astype(long, order='C', casting='safe', copy=True)
assert adj_mat_copy.flags['C_CONTIGUOUS']
cdef numpy.ndarray[long, ndim=2, mode='c'] M = adj_mat_copy
cdef numpy.ndarray[long, ndim=2, mode='c'] path = numpy.zeros([n, n], dtype=numpy.int64)
cdef unsigned int i, j, k
cdef long M_ij, M_ik, cost_ikkj
cdef long* M_ptr = &M[0,0]
cdef long* M_i_ptr
cdef long* M_k_ptr
# set unreachable nodes distance to 510
for i in range(n):
for j in range(n):
if i == j:
M[i][j] = 0
elif M[i][j] == 0:
M[i][j] = 510
# floyed algo
for k in range(n):
M_k_ptr = M_ptr + n*k
for i in range(n):
M_i_ptr = M_ptr + n*i
M_ik = M_i_ptr[k]
for j in range(n):
cost_ikkj = M_ik + M_k_ptr[j]
M_ij = M_i_ptr[j]
if M_ij > cost_ikkj:
M_i_ptr[j] = cost_ikkj
path[i][j] = k
# set unreachable path to 510
for i in range(n):
for j in range(n):
if M[i][j] >= 510:
path[i][j] = 510
M[i][j] = 510
return M, path
def get_all_edges(path, i, j):
cdef unsigned int k = path[i][j]
if k == 0:
return []
else:
return get_all_edges(path, i, k) + [k] + get_all_edges(path, k, j)