Use unpacking operator on dicts to prevent constructing intermediate objects (#6040)

3 files changed, 8 insertions, 15 deletions

diff --git a/networkx/readwrite/json_graph/adjacency.py b/networkx/readwrite/json_graph/adjacency.py
index 0cb866a4..066b78f1 100644
--- a/networkx/readwrite/json_graph/adjacency.py
+++ b/networkx/readwrite/json_graph/adjacency.py
@@ -1,5 +1,3 @@
-from itertools import chain
-
 import networkx as nx
 
 __all__ = ["adjacency_data", "adjacency_graph"]
@@ -70,15 +68,15 @@ def adjacency_data(G, attrs=_attrs):
     data["nodes"] = []
     data["adjacency"] = []
     for n, nbrdict in G.adjacency():
-        data["nodes"].append(dict(chain(G.nodes[n].items(), [(id_, n)])))
+        data["nodes"].append({**G.nodes[n], id_: n})
         adj = []
         if multigraph:
             for nbr, keys in nbrdict.items():
                 for k, d in keys.items():
-                    adj.append(dict(chain(d.items(), [(id_, nbr), (key, k)])))
+                    adj.append({**d, id_: nbr, key: k})
         else:
             for nbr, d in nbrdict.items():
-                adj.append(dict(chain(d.items(), [(id_, nbr)])))
+                adj.append({**d, id_: nbr})
         data["adjacency"].append(adj)
     return data
 
diff --git a/networkx/readwrite/json_graph/node_link.py b/networkx/readwrite/json_graph/node_link.py
index 86d3a4c2..c5957f67 100644
--- a/networkx/readwrite/json_graph/node_link.py
+++ b/networkx/readwrite/json_graph/node_link.py
@@ -169,18 +169,15 @@ def node_link_data(
         "directed": G.is_directed(),
         "multigraph": multigraph,
         "graph": G.graph,
-        "nodes": [dict(chain(G.nodes[n].items(), [(name, n)])) for n in G],
+        "nodes": [{**G.nodes[n], name: n} for n in G],
     }
     if multigraph:
         data[link] = [
-            dict(chain(d.items(), [(source, u), (target, v), (key, k)]))
+            {**d, source: u, target: v, key: k}
             for u, v, k, d in G.edges(keys=True, data=True)
         ]
     else:
-        data[link] = [
-            dict(chain(d.items(), [(source, u), (target, v)]))
-            for u, v, d in G.edges(data=True)
-        ]
+        data[link] = [{**d, source: u, target: v} for u, v, d in G.edges(data=True)]
     return data
 
 
diff --git a/networkx/readwrite/json_graph/tree.py b/networkx/readwrite/json_graph/tree.py
index 3e9a4c95..5ec000d5 100644
--- a/networkx/readwrite/json_graph/tree.py
+++ b/networkx/readwrite/json_graph/tree.py
@@ -73,16 +73,14 @@ def tree_data(G, root, ident="id", children="children"):
             return []
         children_ = []
         for child in nbrs:
-            d = dict(chain(G.nodes[child].items(), [(ident, child)]))
+            d = {**G.nodes[child], 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
+    return {**G.nodes[root], ident: root, children: add_children(root, G)}
 
 
 def tree_graph(data, ident="id", children="children"):