Header image with the text “NPAP – A Python library for partitioning and aggregating network graphs,” featuring colorful network diagrams in yellow, green, and blue on a wavy blue background.

NPAP (Network Partitioning and Aggregation in Python) is an open-source Python toolbox designed to simplify and standardize the reduction of complex network models. It provides a flexible framework for partitioning large-scale graphs and aggregating them into smaller, computationally tractable representations while preserving key structural and functional properties.

It is particularly designed for applications in electrical energy systems, where large and highly detailed grid models often need to be simplified to enable efficient computation. NPAP is built on NetworkX and provides a modular, strategy-based architecture for flexible and transparent network reduction.

Motivation

Modern energy system models represent power grids with a high level of spatial and technical detail. While this level of detail is essential for accurate analysis, it also leads to increased computational complexity and longer runtimes. NPAP helps reduce this complexity by systematically simplifying networks while preserving key structural and electrical characteristics.

Functionality

NPAP combines two main steps: network partitioning and aggregation. In the first step, nodes are grouped into clusters based on criteria such as geographic proximity, electrical distance, or structural similarity. A range of clustering methods is available, including K-Means, K-Medoids, DBSCAN, HDBSCAN, and hierarchical clustering.

In the second step, these clusters are aggregated into representative nodes. During this process, properties such as load, generation capacity, coordinates, and line parameters are systematically combined. NPAP provides predefined aggregation methods as well as the flexibility to define custom aggregation strategies.

Use Cases

NPAP is particularly suitable for reducing power grid models in energy system applications, for example in combination with tools such as PyPSA or expansion planning models. In addition, it can be used for scenario analysis, machine learning applications, or general graph reduction tasks.

Screenshot of Python code for network partitioning with `npap`, showing steps to load data, aggregate parallel edges, partition, and visualize a network, including sample code.

Integration

The library integrates seamlessly into Python-based workflows and works directly with NetworkX graphs as well as tabular data formats such as CSV files. This makes it easy to incorporate NPAP into existing modeling and analysis pipelines.

How to Start

Getting started with NPAP is straightforward. The library can be accessed via its GitHub repository and integrated into existing Python projects. The documentation provides step-by-step examples, guiding users from loading a network to selecting a partitioning strategy and performing aggregation.

For a first workflow, users typically load a network, choose an appropriate partitioning strategy, and then apply aggregation. The modular design of NPAP allows for easy comparison of different strategies and adaptation to specific modeling needs.

Funding agency

Funded by the European Union (ERC, NetZero-Opt, 101116212). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them.

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