Graph I/O¶

PyGraphina supports multiple formats for saving and loading graphs.

Supported Formats¶

Format	Read	Write	Best For
Edge List	Yes	Yes	Simple, human-readable
JSON	Yes	Yes	Data interchange
Binary	Yes	Yes	Speed, compact storage
GraphML	No	Yes	Standard graph format

Edge List Format¶

Simple text format with edges, one per line.

import pygraphina as pg

g = pg.PyGraph()
a, b, c = g.add_node(1), g.add_node(2), g.add_node(3)
g.add_edge(a, b, 1.0)
g.add_edge(b, c, 2.0)

# Save as edge list
g.save_edge_list("graph.txt", sep=" ")

# Load from edge list
g = pg.PyGraph()
num_nodes, num_edges = g.load_edge_list("graph.txt", sep=" ")

File format:

source target weight
0 1 1.0
1 2 2.0
2 3 1.5

JSON Format¶

Structured format with nodes and edges.

# Save as JSON
g.save_json("graph.json")

# Load from JSON
g = pg.PyGraph()
g.load_json("graph.json")

Binary Format¶

Compact, fast format for large graphs.

# Save as binary
g.save_binary("graph.bin")

# Load from binary
g = pg.PyGraph()
g.load_binary("graph.bin")

GraphML Format¶

Standard XML-based graph format.

# Save as GraphML
g.save_graphml("graph.graphml")

Can be loaded in other tools (Gephi, Cytoscape, etc.).

Example: Loading and Saving¶

import pygraphina as pg

# Create and modify a graph
g = pg.PyGraph()
for i in range(100):
    g.add_node(i)

for i in range(99):
    g.add_edge(i, i + 1, 1.0)

# Save in multiple formats
g.save_edge_list("graph.txt")
g.save_json("graph.json")
g.save_binary("graph.bin")
g.save_graphml("graph.graphml")

# Load in different format
g2 = pg.PyGraph()
g2.load_edge_list("graph.txt")

# Verify
assert g2.node_count() == g.node_count()
assert g2.edge_count() == g.edge_count()

Separator Options for Edge Lists¶

Common separators:

" " (space) - default, human-readable
"," (comma) - CSV format
"\t" (tab) - tab-separated

# CSV format
g.save_edge_list("graph.csv", sep=",")
g2 = pg.PyGraph()
g2.load_edge_list("graph.csv", sep=",")

# Tab-separated
g.save_edge_list("graph.tsv", sep="\t")
g3 = pg.PyGraph()
g3.load_edge_list("graph.tsv", sep="\t")

Format Comparison¶

Property	Edge List	JSON	Binary
Human-Readable	Yes	Yes	No
Compact	Moderate	No	Yes
Fast	Moderate	Slow	Fast
Standard	Yes	Yes	No

Tips¶

Use edge list for portability - Works with most tools
Use binary for speed - Fastest I/O for large graphs
Use JSON for interchange - Inspect and modify easily
Use GraphML for visualization - Standard format for graph tools