Skip to main content

Flowty Network Optimization Solver

Project description


Install with

pip install flowty


Install the 64-bit version of python.


Install Fortran to work with the BLAS and LAPACK.

On apt-get compatible distributions do

apt-get update
apt-get install libgfortran5

Quick Start

Let's solve the vehicle routing problem with time windows.

The objective is to minimize the total cost of routing vehicles from a central depot to a set of customers. Each customer must be visited exactly once within a specified time window to deliver their required demand, each customer has a service time it takes to unload the vehicle (modeled within the out-going travel time), and each vehicle has a maximum capacity of goods to deliver. If a vehicle arrives early it is allowed to wait for the customer's time window to start.

# Vehicle Routing Problem with Time Windows

from flowty import Model, xsum
from flowty.datasets import vrp_rep

bunch = vrp_rep.fetch_vrp_rep("solomon-1987-r1", instance="R102_025")
name, n, es, c, d, Q, t, a, b, x, y = bunch["instance"]

m = Model()

# one graph, it is identical for all vehicles
g = m.addGraph(obj=c, edges=es, source=0, sink=n - 1, L=1, U=n - 2, type="B")

# adds resources variables to the graph.
# demand and capacity
    graph=g, consumptionType="V", weight=d, boundsType="V", lb=0, ub=Q, name="d"

# travel time and customer time windows
    graph=g, consumptionType="E", weight=t, boundsType="V", lb=a, ub=b, name="t"

# set partition constriants ensure customers are only visited once
for i in range(n)[1:-1]:
    m += xsum(x * 1 for x in g.vars if i == x.source) == 1

# packing set - at most one of these variables can be set. Helps the algorithm
for i in range(n)[1:-1]:
    m.addPackingSet([x for x in g.vars if i == x.source])

status = m.optimize()
print(f"ObjectiveValue {m.objectiveValue}")

# get the variable values
for var in m.vars:
    if var.x > 0:
        print(f"{} = {var.x}")

Visit to get to know more.


The community license is a license to the general community which may have limited features and additional restrictions. For an unlimited commercial, academic or trial license contact Flowty at

Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distributions

No source distribution files available for this release.See tutorial on generating distribution archives.

Built Distribution

flowty-1.2.8-py3-none-any.whl (6.3 MB view hashes)

Uploaded Python 3

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page