def grid_graph(dim, periodic=False):
"""Returns the *n*-dimensional grid graph.
The dimension *n* is the length of the list `dim` and the size in
each dimension is the value of the corresponding list element.
Parameters
----------
dim : list or tuple of numbers or iterables of nodes
'dim' is a tuple or list with, for each dimension, either a number
that is the size of that dimension or an iterable of nodes for
that dimension. The dimension of the grid_graph is the length
of `dim`.
periodic : bool or iterable
If `periodic` is True, all dimensions are periodic. If False all
dimensions are not periodic. If `periodic` is iterable, it should
yield `dim` bool values each of which indicates whether the
corresponding axis is periodic.
Returns
-------
NetworkX graph
The (possibly periodic) grid graph of the specified dimensions.
Examples
--------
To produce a 2 by 3 by 4 grid graph, a graph on 24 nodes:
>>> from networkx import grid_graph
>>> G = grid_graph(dim=(2, 3, 4))
>>> len(G)
24
>>> G = grid_graph(dim=(range(7, 9), range(3, 6)))
>>> len(G)
6
"""
from networkx.algorithms.operators.product import cartesian_product
if not dim:
return empty_graph(0)
if iterable(periodic):
func = (cycle_graph if p else path_graph for p in periodic)
else:
func = repeat(cycle_graph if periodic else path_graph)
G = next(func)(dim[0])
for current_dim in dim[1:]:
Gnew = next(func)(current_dim)
G = cartesian_product(Gnew, G)
# graph G is done but has labels of the form (1, (2, (3, 1))) so relabel
H = relabel_nodes(G, flatten)
return H
def test_iterable():
assert not iterable(None)
assert not iterable(10)
assert iterable([1, 2, 3])
assert iterable((1, 2, 3))
assert iterable({1: "A", 2: "X"})
assert iterable("ABC")
def grid_2d_graph(m, n, periodic=False, create_using=None):
"""Returns the two-dimensional grid graph.
The grid graph has each node connected to its four nearest neighbors.
Parameters
----------
m, n : int or iterable container of nodes
If an integer, nodes are from `range(n)`.
If a container, elements become the coordinate of the nodes.
periodic : bool or iterable
If `periodic` is True, both dimensions are periodic. If False, none
are periodic. If `periodic` is iterable, it should yield 2 bool
values indicating whether the 1st and 2nd axes, respectively, are
periodic.
create_using : NetworkX graph constructor, optional (default=nx.Graph)
Graph type to create. If graph instance, then cleared before populated.
Returns
-------
NetworkX graph
The (possibly periodic) grid graph of the specified dimensions.
"""
G = empty_graph(0, create_using)
row_name, rows = m
col_name, cols = n
G.add_nodes_from((i, j) for i in rows for j in cols)
G.add_edges_from(
((i, j), (pi, j)) for pi, i in pairwise(rows) for j in cols)
G.add_edges_from(
((i, j), (i, pj)) for i in rows for pj, j in pairwise(cols))
if iterable(periodic):
periodic_r, periodic_c = periodic
else:
periodic_r = periodic_c = periodic
if periodic_r and len(rows) > 2:
first = rows[0]
last = rows[-1]
G.add_edges_from(((first, j), (last, j)) for j in cols)
if periodic_c and len(cols) > 2:
first = cols[0]
last = cols[-1]
G.add_edges_from(((i, first), (i, last)) for i in rows)
# both directions for directed
if G.is_directed():
G.add_edges_from((v, u) for u, v in G.edges())
return G
def test_graph_iterable():
K = nx.complete_graph(10)
assert iterable(K)
assert iterable(K.nodes())
assert iterable(K.edges())
