holgerbrandl/kortools

A kotlin API around OR Tools

kortools

A kotlin API around OR Tools

kortools provides a more natural API to express optimization problems on the JVM with the great OR as solver backend.

kortools is designed for simulation practitioners, process analysts and industrial engineers, who need to go beyond the limitations of existing simulation tools to model and optimize their business-critical use-cases.

Example

// Create the linear solver with the GLOP backend.
val solver = createSolver(SolverId.GLOP) {
    // Create the variables x and y.
    val x by makeVariable(0.0, 1.0)
    val y by makeVariable(0.0, 1.0)

    // Create a linear constraint, 0 <= x + y <= 2.
    constraint("ct", 0.0 to 2.0) {
        x withCoeff 1.0
        y withCoeff 1.0
    }

    // Create the objective function, 3 * x + y.
    maximize {
        3 * x + y
    }
}

// solve the problem
solver.solve()

with(solver) {
    println("Solution:")
    println("Number of variables = " + numVariables())
    println("Number of constraints = " + numConstraints())
    println("Objective value = " + objective().value())
    println("x = " + variable("x").solutionValue())
    println(
        "y = " + variable("y").solutionValue()
    )
}

Jupyter

An easy way to get started with kortools is with jupyter, you simply need to install the kotlin-jupyter kernel and load the library with:

%use kortools

See here for a notebook example.

Setup

Add the following artifact to your gradle.build

compile "com.github.holgerbrandl:kortools:0.5"

You can also use JitPack with Maven or Gradle to build the latest snapshot as a dependency in your project.

repositories {
    maven { url 'https://jitpack.io' }
}
dependencies {
        compile 'com.github.holgerbrandl:kortools:-SNAPSHOT'
}

To build and install it into your local maven cache, simply clone the repo and run

./gradlew install

Misc References

https://github.com/google/or-tools/tree/stable/ortools/linear_solver/samples