#!/usr/bin/env python
#
# Author: Patrick Hung (patrickh @caltech)
# Author: Mike McKerns (mmckerns @caltech and @uqfoundation)
# Copyright (c) 1997-2016 California Institute of Technology.
# Copyright (c) 2016-2021 The Uncertainty Quantification Foundation.
# License: 3-clause BSD.  The full license text is available at:
#  - https://github.com/uqfoundation/mystic/blob/master/LICENSE
"""
Testing Rosenbrock's Function.

This is a very popular function for testing minimization algorithm.
The following provides tests for both bounded and unbounded minimization
of the Rosenbrock function with Differential Evolution.

For direct searches, Nelder-Mead does very well on this problem. 
For a direct comparison between DE and steepest-descent solvers, run
test_rosenbrock*.py (or optimize.py in scipy.optimize).
"""

from mystic.solvers import DifferentialEvolutionSolver, diffev
from mystic.termination import ChangeOverGeneration, VTR
from mystic.models import rosen
from mystic.monitors import Monitor, VerboseMonitor

from mystic.tools import random_seed
random_seed(123)

ND = 3
NP = 30
#MAX_GENERATIONS = 29
MAX_GENERATIONS = 99999

def main():
    solver = DifferentialEvolutionSolver(ND, NP)

    solver.SetRandomInitialPoints(min = [0]*ND, max = [2]*ND)
    solver.SetEvaluationLimits(generations=MAX_GENERATIONS)

    solver.Solve(rosen, termination = VTR(0.0001), \
                 CrossProbability=0.5, ScalingFactor=0.6, disp=1)

    solution = solver.bestSolution
   #print("Current function value: %s" % solver.bestEnergy)
   #print("Iterations: %s" % solver.generations)
   #print("Function evaluations: %s" % solver.evaluations)
  
    print(solution)



if __name__ == '__main__':
    from numpy import inf
    print("without bounds...")
    from timeit import Timer
    print("Differential Evolution")
    print("======================")
    t = Timer("main()", "from __main__ import main")
    timetaken =  t.timeit(number=1)
    print("CPU Time: %s\n" % timetaken)

    print("with bounds...")
    import time
    times = []
    algor = []

    print("Differential Evolution")
    print("======================")
    start = time.time()
    esow= Monitor()
    ssow= Monitor()
   #ssow= VerboseMonitor(1)

  # import random
 #  xinit = [random.random() for j in range(ND)]
    xinit = [0.8,1.2,0.7]
  # xinit = [0.8,1.2,1.7]             #... better when using "bad" range
    min = [-0.999, -0.999, 0.999]     #XXX: behaves badly when large range
    max = [200.001, 100.001, inf]     #... for >=1 x0 out of bounds; (up xtol)
  # min = [-0.999, -0.999, -0.999]
  # max = [200.001, 100.001, inf]
 #  min = [-0.999, -0.999, 0.999]     #XXX: tight range and non-randomness
 #  max = [2.001, 1.001, 1.001]       #...: is _bad_ for DE solvers

   #print(diffev(rosen,xinit,NP,retall=0,full_output=0))
    solver = DifferentialEvolutionSolver(len(xinit), NP)
    solver.SetInitialPoints(xinit)
    solver.SetStrictRanges(min,max)
    solver.SetEvaluationLimits(generations=MAX_GENERATIONS)
    solver.SetEvaluationMonitor(esow)
    solver.SetGenerationMonitor(ssow)
    solver.Solve(rosen, VTR(0.0001), \
                 CrossProbability=0.5, ScalingFactor=0.6, disp=1)
    sol = solver.bestSolution
    print(sol)
   #print("Current function value: %s" % solver.bestEnergy)
   #print("Iterations: %s" % solver.generations)
   #print("Function evaluations: %s" % solver.evaluations)
 
    times.append(time.time() - start)
    algor.append('Differential Evolution\t')

    for k,t in zip(algor,times):
        print("%s\t -- took %s" % (k, t))

   #print(len(esow.x))
   #print(len(ssow.x))
   #print("\nstep x:\n%s" % ssow.x[1:10][0])
   #print("\nstep y:\n%s" % ssow.y[1:10][0])



# end of file
