from itertools import chain
import networkx as nx
__all__ = ["tree_data", "tree_graph"]
_attrs = dict(id="id", children="children")
[docs]def tree_data(G, root, attrs=_attrs):
"""Returns data in tree format that is suitable for JSON serialization
and use in Javascript documents.
Parameters
----------
G : NetworkX graph
G must be an oriented tree
root : node
The root of the tree
attrs : dict
A dictionary that contains two keys 'id' and 'children'. The
corresponding values provide the attribute names for storing
NetworkX-internal graph data. The values should be unique. Default
value: :samp:`dict(id='id', children='children')`.
If some user-defined graph data use these attribute names as data keys,
they may be silently dropped.
Returns
-------
data : dict
A dictionary with node-link formatted data.
Raises
------
NetworkXError
If values in attrs are not unique.
Examples
--------
>>> from networkx.readwrite import json_graph
>>> G = nx.DiGraph([(1, 2)])
>>> data = json_graph.tree_data(G, root=1)
To serialize with json
>>> import json
>>> s = json.dumps(data)
Notes
-----
Node attributes are stored in this format but keys
for attributes must be strings if you want to serialize with JSON.
Graph and edge attributes are not stored.
The default value of attrs will be changed in a future release of NetworkX.
See Also
--------
tree_graph, node_link_data, node_link_data
"""
if G.number_of_nodes() != G.number_of_edges() + 1:
raise TypeError("G is not a tree.")
if not G.is_directed():
raise TypeError("G is not directed.")
id_ = attrs["id"]
children = attrs["children"]
if id_ == children:
raise nx.NetworkXError("Attribute names are not unique.")
def add_children(n, G):
nbrs = G[n]
if len(nbrs) == 0:
return []
children_ = []
for child in nbrs:
d = dict(chain(G.nodes[child].items(), [(id_, child)]))
c = add_children(child, G)
if c:
d[children] = c
children_.append(d)
return children_
data = dict(chain(G.nodes[root].items(), [(id_, root)]))
data[children] = add_children(root, G)
return data
[docs]def tree_graph(data, attrs=_attrs):
"""Returns graph from tree data format.
Parameters
----------
data : dict
Tree formatted graph data
Returns
-------
G : NetworkX DiGraph
attrs : dict
A dictionary that contains two keys 'id' and 'children'. The
corresponding values provide the attribute names for storing
NetworkX-internal graph data. The values should be unique. Default
value: :samp:`dict(id='id', children='children')`.
Examples
--------
>>> from networkx.readwrite import json_graph
>>> G = nx.DiGraph([(1, 2)])
>>> data = json_graph.tree_data(G, root=1)
>>> H = json_graph.tree_graph(data)
Notes
-----
The default value of attrs will be changed in a future release of NetworkX.
See Also
--------
tree_graph, node_link_data, adjacency_data
"""
graph = nx.DiGraph()
id_ = attrs["id"]
children = attrs["children"]
def add_children(parent, children_):
for data in children_:
child = data[id_]
graph.add_edge(parent, child)
grandchildren = data.get(children, [])
if grandchildren:
add_children(child, grandchildren)
nodedata = {
str(k): v for k, v in data.items() if k != id_ and k != children
}
graph.add_node(child, **nodedata)
root = data[id_]
children_ = data.get(children, [])
nodedata = {str(k): v for k, v in data.items() if k != id_ and k != children}
graph.add_node(root, **nodedata)
add_children(root, children_)
return graph