pylmcf 0.9.4

Python bindings for Network Simplex algorithm from LEMON library

pylmcf: Python bindings for Min Cost Flow algorithm from LEMON graph library

Overview

pylmcf provides Python bindings for the Min Cost Flow algorithm implemented in the LEMON graph library. It enables efficient network flow optimization in Python applications. It is used by wnet (a Python package enabling the efficient computation of Wasserstein and Truncated Wassersten distance between multidimensional distributions) and wnetalign (A Python package enabling efficient alignment of MS or NMR spectra)

Features

• Fast min cost flow computation using C++ backend
• Easy-to-use Python API
• Supports directed graphs, capacities, costs, and supplies/demands

Installation

pip install pylmcf

Usage

import numpy as np
import pylmcf

# Create a graph with 3 nodes, labelled 0, 1, 2, and edges 0->1, 0->2, 1->2
no_nodes = 3
node_supply = np.array([5, 0, -5])

edge_starts     = np.array([0, 0, 1])
edge_ends       = np.array([1, 2, 2])
edge_costs      = np.array([1, 3, 5])
edge_capacities = np.array([1, 2, 3])

G = pylmcf.Graph(3, edge_starts, edge_ends)
G.set_node_supply(node_supply)
G.set_edge_costs(edge_costs)
G.set_edge_capacities(edge_capacities)

G.show()

# Run the Min Cost Flow algorithm
G.solve()

# Retrieve the flow values
G.result()
# returns: np.array([1, 2, 1]))

# Retrieve the total cost of the flow
G.total_cost()
# == 12

Requirements

• Python 3.7+

Licence

pylmcf is published under Boost licence. LEMON (which resides in src/pylmcf/cpp/lemon subdirectory) is also covered by Boost licence.

References

• LEMON Graph Library
• wnet package
• wnetalign package
• Min Cost Flow Problem