What is Leiden Algorithm

The Leiden algorithm is a hierarchical clustering algorithm used for detecting communities (clusters) within networks by optimizing modularity, which measures the quality of the network's division into clusters. It builds upon the Louvain algorithm but addresses its limitations, particularly the tendency to produce poorly connected communities. Leiden achieves this by introducing a refinement phase that allows for the dynamic reassignment of nodes and the breaking down of communities into smaller, well-connected ones. 

Here's a more detailed breakdown:

Key aspects of the Leiden algorithm:

Hierarchical Clustering:

It operates by iteratively merging or splitting communities to find the best possible structure. 

Modularity Optimization:

The algorithm aims to maximize the modularity of the network, which indicates how densely connected nodes within a community are, compared to a random network. 

Addressing Louvain Limitations:

Leiden improves upon Louvain by introducing a refinement phase that ensures communities are well-connected and that no nodes are left in disconnected communities. 

Addressing Louvain Limitations:

Leiden improves upon Louvain by introducing a refinement phase that ensures communities are well-connected and that no nodes are left in disconnected communities. 

Refinement Phase:

This phase allows nodes to dynamically reassign themselves across overlapping clusters, leading to more accurate and meaningful community structures. 

Aggregate Network:

The algorithm creates an aggregate network based on the refined partition, using the non-refined partition as an initial partition for the aggregate network. 

Iterative Process:

The process of local moving and refinement is repeated until no further improvements can be made, resulting in a stable and well-defined community structure.