s2mflow 0.1.6

Meta-generator: generating multicommodity flow instances from single-commodity flow instances.

s2mflow

A meta-generator for generating multicommodity flow instances from single-commodity flow instances.

s2mflow is a Python library with a high-speed Rust core (via PyO3) designed to transform single-commodity minimum-cost flow (MCF) instances into minimum-cost multicommodity flow (MCMCF) instances. It is built for researchers in Operations Research, Mathematical Optimization, and Network Optimization who need to generate reproducible, scalable test data.

Key Features

• Blazing Fast: Core logic implemented in Rust for zero-overhead data handling.
• DIMACS Compatible: Load standard .min single-commodity files.
• Custom MCMCF Format: Introduces the .mcfmin format for multicommodity data.
• Supply Partitioning:
  • uniform: Equal distribution of supply and demand across commodities.
  • spread: Randomized, heterogeneous distribution of supply and demand across commodities.
• Randomizing Capacities and Costs: Functionality for generating randomized commodity capacities and commodity costs for each arc.
• Network Utilities: Support for identifying incoming and outgoing edges.

Installation

pip install s2mflow

Quick Start

# .min example data:
# c  *** Minimum cost flow ***
# c
# p min 5 10
# n 1 10
# n 5 -10
# a 1 2 0 10 9
# a 1 4 0 16 2
# a 2 4 0 10 10
# a 2 3 0 10 1
# a 3 5 0 10 10
# a 3 2 0 20 2
# a 3 4 0 17 9
# a 4 3 0 10 9
# a 4 1 0 10 3
# a 4 2 0 19 2

import s2mflow

# 1. Load a single-commodity network
network = s2mflow.load_min_instance("input.min")

# 2. Generate multicommodity data for 3 commodities
mc_data = s2mflow.generate_multi_commodity_data(
    instance=network,
    num_commodities=3,
    is_uniform=False,
    seed=42,
)

# 3. Save as a multi-commodity instance
s2mflow.save_multi_commodity_instance("output.mcfmin", network, mc_data)

# c Multicommodity flow generated by s2mflow
# p min 5 10 3 0 0 0 42
# n 1 10 2 3 5
# n 5 -10 -2 -3 -5
# a 1 2 0 10 10 9
# a 1 4 0 16 16 2
# a 2 4 0 10 10 10
# a 2 3 0 10 10 1
# a 3 5 0 10 10 10
# a 3 2 0 20 20 2
# a 3 4 0 17 17 9
# a 4 3 0 10 10 9
# a 4 1 0 10 10 3
# a 4 2 0 19 19 2

Citing

If you use s2mflow in your research, please cite the software:

@software{s2mflow2026,
  author = {Broesamle, Felix P. and Nickel, Stefan},
  title = {s2mflow: A Meta-generator for Multicommodity Flow Instances},
  year = {2026},
  url = {https://github.com/FelixBroesamle/s2mflow}
}

Resources

• Documentation: s2mflow.readthedocs.io
• PyPI Package: pypi.org/project/s2mflow

License

Distributed under the MIT License. See LICENSE for more information.