#!/usr/bin/env python
"""
Task for RosenBrock Function
==============================
"""
import numpy
from orion.benchmark.task.base import BenchmarkTask
[docs]class RosenBrock(BenchmarkTask):
"""`RosenBrock function <http://infinity77.net/global_optimization/test_functions_nd_R.html#go_benchmark.Rosenbrock>`_
as benchmark task"""
def __init__(self, max_trials=20, dim=2):
self.dim = dim
super().__init__(max_trials=max_trials, dim=dim)
[docs] def call(self, x):
"""Evaluate a n-D rosenbrock function."""
x = numpy.asarray(x)
summands = 100 * (x[1:] - x[:-1] ** 2) ** 2 + (1 - x[:-1]) ** 2
y = numpy.sum(summands)
return [dict(name="rosenbrock", type="objective", value=y)]
[docs] def get_search_space(self):
"""Return the search space for the task objective function"""
rspace = {"x": f"uniform(-5, 10, shape={self.dim})"}
return rspace