Graph Views

Views provide read-only access to graph components (nodes, edges, and degrees) with a Pythonic API similar to NetworkX.

NodeView

Returned by G.nodes. It behaves like a list of nodes or a dict of node attributes.

Usage

import pygraphina as pg

g = pg.PyGraph()
g.add_node(1, attr=100)

# Iteration
for n in g.nodes:
    print(n)

# Membership
if 1 in g.nodes:
    print("Node 1 exists")

# Attribute Access
print(g.nodes[1])  # {'attr': 100}

# Data Access
print(list(g.nodes.data("attr")))  # [(1, 100)]

Methods

• __iter__(): Iterate over node IDs.
• __len__(): Number of nodes.
• __contains__(n): Check if node n exists.
• __getitem__(n): Get attributes for node n (returns dict).
• data(name=None, default=None): Return a NodeDataView to iterate over (node, attribute_value) tuples.

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EdgeView

Returned by G.edges. Provides access to edges and their weights.

Usage

g.add_edge(1, 2, 3.5)

# Iteration
for u, v in g.edges:
    print(u, v)

# Membership
if (1, 2) in g.edges:
    print("Edge exists")

# Attribute Access (Weights)
print(g.edges[1, 2])  # {'weight': 3.5}

# Data Access
print(list(g.edges.data("weight")))  # [(1, 2, 3.5)]

Methods

• __iter__(): Iterate over edges (u, v).
• __len__(): Number of edges.
• __contains__((u, v)): Check if edge exists.
• __getitem__((u, v)): Get attributes (weight) for edge u-v.
• data(name="weight", default=None): Return an EdgeDataView to iterate over (u, v, value).

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DegreeView

Returned by G.degree. Provides access to node degrees.

Usage

# Access single node degree
print(g.degree[1])  # 2

# Iterate over (node, degree)
for n, d in g.degree:
    print(f"Node {n} has degree {d}")

Methods

• __iter__(): Iterate over (node, degree) pairs.
• __getitem__(n): Get degree of node n.
• __len__(): Number of nodes.
• __call__(nbunch=None, weight=None): (Advanced) Get degree for subset of nodes or weighted degree.