Leiden Flamegraph

A C++ implementation of the Leiden community detection algorithm that visualizes hierarchical community structures as flame graphs. Takes a graph and finds communities within it, then shows how those communities merge together at different levels as a flame graph visualization.

Example

# Run on a graph
./leiden-flamegraph-main my_network.edgelist

# Creates hierarchy.folded and leiden.svg

Input format

Simple edge list format:

0 1
0 2  
1 2
3 4
3 5
4 5

Each line is an edge between two nodes. The algorithm treats graphs as undirected.

Building

chmod +x build.sh
./build.sh

Requires C++23 and cmake.

Output

• hierarchy.folded: Flame graph data in folded stack format
• leiden.svg: Visual flame graph (if flamegraph.pl is installed)

The flame graph shows:

• Width: Number of nodes in each community
• Height: Hierarchy level (deeper = more refined)
• Branching: How communities split and merge