Attributes

Attributes define problem features and automatically enable matching constraint generators and evaluators.

Available Attributes

Attribute	Entity	Description
GeoNode	Node	x, y coordinates for distance calculation
Consumer	Client	Demand at a client
Stock	Vehicle	Vehicle capacity
Rendezvous	Node	Time window bounds (earliest, latest)
ServiceQuery	Client	Service time at a node
Profiter	Client	Profit value for orienteering problems (TOP)
Pickup	Client	Pickup demand for pickup & delivery
Delivery	Client	Delivery demand for pickup & delivery
Synced	Client	Temporal synchronization constraints
SoftTimeWindows	Client	Penalty-based soft time windows

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Problem Variants by Attributes

Problem	Required Attributes
TSP	GeoNode
VRP	GeoNode
CVRP	GeoNode, Consumer, Stock
VRPTW	GeoNode, Rendezvous, ServiceQuery
CVRPTW	GeoNode, Consumer, Stock, Rendezvous, ServiceQuery
VRPTWTD	All above + Synced
PDVRP	GeoNode, Pickup, Delivery, Stock
TOP	GeoNode, Profiter, Rendezvous

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Usage

Python

import routing
from routing.constants import Attribute

routing.init()

problem = routing.Problem()

# Depot
depot = problem.add_depot(0)
depot.add_attribute(Attribute.GEONODE, x=0, y=0)
depot.add_attribute(Attribute.RENDEZVOUS, open=0, close=1000)

# Client
client = problem.add_client(1)
client.add_attribute(Attribute.GEONODE, x=10, y=20)
client.add_attribute(Attribute.CONSUMER, demand=5)
client.add_attribute(Attribute.RENDEZVOUS, open=0, close=200)
client.add_attribute(Attribute.SERVICE_QUERY, service_time=10)

# Vehicle
vehicle = problem.add_vehicle(0)
vehicle.add_attribute(Attribute.STOCK, capacity=100)

# Solve (attributes auto-enabled!)
solution = routing.solve(problem, "ga", timeout=30)

Attribute Parameters:

Enum	Parameters
Attribute.GEONODE	x, y
Attribute.CONSUMER	demand
Attribute.STOCK	capacity
Attribute.RENDEZVOUS	open, close
Attribute.SERVICE_QUERY	service_time
Attribute.PROFITER	profit
Attribute.PICKUP	demand
Attribute.DELIVERY	demand

C++

In C++, you use template methods to add attributes. Attributes are automatically enabled when added:

// Add depot with attributes
auto* depot = problem.addDepot(0);
depot->addAttribute<GeoNode>(0.0, 0.0);           // Auto-enables GeoNode
depot->addAttribute<Rendezvous>(0.0, 1000.0);     // Auto-enables Rendezvous

// Add client with attributes
auto* client = problem.addClient(1);
client->addAttribute<GeoNode>(10.0, 20.0);        // Coordinates
client->addAttribute<Consumer>(5);                 // Auto-enables Consumer
client->addAttribute<Rendezvous>(0.0, 200.0);     // Time window
client->addAttribute<ServiceQuery>(10.0);          // Auto-enables ServiceQuery

// Add vehicle with attributes
auto* vehicle = problem.addVehicle(0);
vehicle->addAttribute<Stock>(20);                  // Auto-enables Stock

// Attributes are automatically enabled!
// You can still explicitly enable if needed:
// problem.enableAttributes<GeoNode, Consumer, Stock>();

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How Attributes Work

Automatic Enabling

When you add an attribute to an entity using add_attribute(), the system automatically:

1. Stores the attribute data on the entity

2. Auto-enables the attribute type on the problem (if not already enabled)

3. Activates constraint generators that depend on that attribute

4. Activates evaluators for solution quality assessment

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Custom Attributes

You can define custom attributes using the CRTP pattern:

struct MyAttribute : public Attribute<MyAttribute> {
    static constexpr const char* name() { return "MyAttribute"; }

    double value;

    explicit MyAttribute(double v) : value(v) {}
};

See Composable System for more details on extending the attribute system.