Crate grb

Crate grb 

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This crate provides Rust bindings for Gurobi Optimizer. It currently requires Gurobi 9.5

§Quick Start

The example below sets up and solves a Mixed Integer Program (MIP). Additional examples covering the more specific aspects of this crate’s API can be found here.

The documention for Model contains most of the details for defining, solving and querying models.

use grb::prelude::*;

let mut model = Model::new("model1")?;

// add decision variables with no bounds
let x1 = add_ctsvar!(model, name: "x1", bounds: ..)?;
let x2 = add_intvar!(model, name: "x2", bounds: ..)?;

// add linear constraints
let c0 = model.add_constr("c0", c!(x1 + 2*x2 >= -14))?;
let c1 = model.add_constr("c1", c!(-4 * x1 - x2 <= -33))?;
let c2 = model.add_constr("c2", c!(2* x1 <= 20 - x2))?;

// model is lazily updated by default
assert_eq!(model.get_obj_attr(attr::VarName, &x1).unwrap_err(), grb::Error::ModelObjectPending);
assert_eq!(model.get_attr(attr::IsMIP)?, 0);

// set the objective function, which updates the model objects (variables and constraints).
// One could also call `model.update()`
model.set_objective(8*x1 + x2, Minimize)?;
assert_eq!(model.get_obj_attr(attr::VarName, &x1)?, "x1");
assert_eq!(model.get_attr(attr::IsMIP)?, 1);

// write model to the file.
model.write("model.lp")?;

// optimize the model
model.optimize()?;
assert_eq!(model.status()?, Status::Optimal);

// Querying a model attribute
assert_eq!(model.get_attr(attr::ObjVal)? , 59.0);

// Querying a model object attributes
assert_eq!(model.get_obj_attr(attr::Slack, &c0)?, -34.5);
let x1_name = model.get_obj_attr(attr::VarName, &x1)?;

// Querying an attribute for multiple model objects
let val = model.get_obj_attr_batch(attr::X, vec![x1, x2])?;
assert_eq!(val, [6.5, 7.0]);

// Querying variables by name
assert_eq!(model.get_var_by_name(&x1_name)?, Some(x1));

§Errors

Due to the nature of C APIs, almost every Gurobi routine can return an error. Unless otherwise stated, if a method or function returns a Result, the error will be Error::FromAPI.

Re-exports§

pub use attribute::attr;
pub use parameter::param;

Modules§

attribute
Gurobi Attributes for models, constraints and variables.
callback
Interface to Gurobi’s callback API
constr
This module contains the structs passed to the Model::add_constr(s) and Model::add_range(s) methods.
expr
Algebraic expressions involving variables used to construct constraints and a helper trait for pretty-printing.
parameter
Gurobi parameters for Env and Model objects. See the manual for a list of parameters and their uses.
prelude
Most commonly used items from this crate bundled for convenient import.

Macros§

add_binvar
Equivalent to calling add_var!(model, Binary, ...)
add_ctsvar
Equivalent to calling add_var!(model, Continuous, ...)
add_intvar
Equivalent to calling add_var!(model, Integer, ...)
add_var
Convenience wrapper around Model::add_var; adds a new variable to a Model object. The macro keyword arguments are optional.
c
A proc-macro for creating constraint objects.

Structs§

AsyncHandle
A handle to an AsyncModel which is currently solving.
AsyncModel
A wrapper around Model that supports async optimisation in the background.
Constr
A linear constraint added to a Model
EmptyEnv
Gurobi environment object (see the Gurobi manual) A Gurobi environment which hasn’t been started yet. Some Gurobi parameters, such as Record need to be set before the environment has been started.
Env
A Gurobi Environment object.
GenConstr
A general constraint added to a Model
Model
Gurobi Model object.
QConstr
A quadratic constraint added to a Model
SOS
An SOS constraint added to a Model
Var
A Gurobi variable.

Enums§

ConstrSense
Sense for new linear/quadratic constraint
Error
The error type for operations in Gurobi Rust API
Expr
An algbraic expression of variables.
GenConstrType
Type of general constraint
ModelSense
Sense of objective function, aka direction of optimisation.
RelaxType
Type of cost function at feasibility relaxation
SOSType
Type of SOS constraint
Status
Status of a model
VarType
Gurobi variable types (see manual)

Constants§

INFINITY
A large constant used by Gurobi to represent numeric infinity.

Traits§

ModelObject
This trait encompasses all Gurobi model objects: Var, Constr, GenConstr, QConstr and SOS. Each ModelObject is associated with a particular model, and can only be used with that model. Each ModelObject also has a unique, fixed 32-bit ID. Gurobi itself uses an i32 to index objects (only positive indices are used), so the 32-bit limitation is already there. Note that IDs are only guaranteed to be unique if the concrete types of the ModelObject are the same and the objects belong to the same model. For example, if v is a Var and c is a Constr, then v and c may have the same ID. Additionally, if s is also a Var, but doesn’t belong to the same Model as v, s and v may have the same ID.

Functions§

version
Returns the version number of Gurobi

Type Aliases§

Result
A specialized std::result::Result for library errors