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from itertools import chain
import networkx as nx
__all__ = ["tree_data", "tree_graph"]
# NOTE: Remove attrs from signature in 3.0
def tree_data(G, root, attrs=None, ident="id", children="children"):
"""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.
.. deprecated:: 2.6
The `attrs` keyword argument is replaced by `ident` and `children`
and will be removed in networkx 3.0
ident : string
Attribute name for storing NetworkX-internal graph data. `ident` must
have a different value than `children`. The default is 'id'.
children : string
Attribute name for storing NetworkX-internal graph data. `children`
must have a different value than `ident`. The default is 'children'.
Returns
-------
data : dict
A dictionary with node-link formatted data.
Raises
------
NetworkXError
If `children` and `ident` attributes are identical.
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.
See Also
--------
tree_graph, node_link_data, adjacency_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.")
# NOTE: to be removed in 3.0
if attrs is not None:
import warnings
msg = (
"\nThe `attrs` keyword argument of tree_data is deprecated\n"
"and will be removed in networkx 3.0.\n"
"It is replaced with explicit `ident` and `children` "
"keyword arguments.\n"
"To make this warning go away and ensure usage is forward\n"
"compatible, replace `attrs` with `ident` and `children,\n"
"for example:\n\n"
" >>> tree_data(G, root, attrs={'id': 'foo', 'children': 'bar'})\n\n"
"should instead be written as\n\n"
" >>> tree_data(G, root, ident='foo', children='bar')\n\n"
"The default values of 'id' and 'children' will not change."
)
warnings.warn(msg, DeprecationWarning, stacklevel=2)
ident = attrs["id"]
children = attrs["children"]
if ident == children:
raise nx.NetworkXError("The values for `id` and `children` must be different.")
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(), [(ident, child)]))
c = add_children(child, G)
if c:
d[children] = c
children_.append(d)
return children_
data = dict(chain(G.nodes[root].items(), [(ident, root)]))
data[children] = add_children(root, G)
return data
def tree_graph(data, attrs=None, ident="id", children="children"):
"""Returns graph from tree data format.
Parameters
----------
data : dict
Tree formatted graph data
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')`.
.. deprecated:: 2.6
The `attrs` keyword argument is replaced by `ident` and `children`
and will be removed in networkx 3.0
ident : string
Attribute name for storing NetworkX-internal graph data. `ident` must
have a different value than `children`. The default is 'id'.
children : string
Attribute name for storing NetworkX-internal graph data. `children`
must have a different value than `ident`. The default is 'children'.
Returns
-------
G : NetworkX DiGraph
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)
See Also
--------
tree_data, node_link_data, adjacency_data
"""
graph = nx.DiGraph()
if attrs is not None:
import warnings
msg = (
"\nThe `attrs` keyword argument of tree_graph is deprecated\n"
"and will be removed in networkx 3.0.\n"
"It is replaced with explicit `ident` and `children` "
"keyword arguments.\n"
"To make this warning go away and ensure usage is\n"
"forward compatible, replace `attrs` with `ident` and `children,\n"
"for example:\n\n"
" >>> tree_graph(data, attrs={'id': 'foo', 'children': 'bar'})\n\n"
"should instead be written as\n\n"
" >>> tree_graph(data, ident='foo', children='bar')\n\n"
"The default values of 'id' and 'children' will not change."
)
warnings.warn(msg, DeprecationWarning, stacklevel=2)
ident = attrs["id"]
children = attrs["children"]
def add_children(parent, children_):
for data in children_:
child = data[ident]
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 != ident and k != children
}
graph.add_node(child, **nodedata)
root = data[ident]
children_ = data.get(children, [])
nodedata = {str(k): v for k, v in data.items() if k != ident and k != children}
graph.add_node(root, **nodedata)
add_children(root, children_)
return graph
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