OptimizationType.MAXIMIZATION does not work with GWO

[timzatko]

Hi!

OptimizationType.MAXIMIZATION does not work when used, I tried it with GWO but it seems to be buggy also with other algorithms.

Steps to reproduce

requirements.txt

NiaPy==2.0.0rc5

Code - taken from here, changed only the optimization type

# encoding=utf8
# This is temporary fix to import module from parent folder
# It will be removed when package is published on PyPI
import sys
sys.path.append('../')
# End of fix

from NiaPy.algorithms.basic import GreyWolfOptimizer
from NiaPy.task import StoppingTask, OptimizationType
from NiaPy.benchmarks import Sphere

# we will run Grey Wolf Optimizer for 5 independent runs
for i in range(5):
    task = StoppingTask(D=10, nFES=10000, optType=OptimizationType.MAXIMIZATION, benchmark=Sphere())
    algo = GreyWolfOptimizer(NP=40)
    best = algo.run(task)
    print(best)

Expected behavior

It should not throw any error.

Actual behavior

TypeError                                 Traceback (most recent call last)
<ipython-input-11-bed1e1b95f2d> in <module>
     14     task = StoppingTask(D=10, nFES=10000, optType=OptimizationType.MAXIMIZATION, benchmark=Sphere())
     15     algo = GreyWolfOptimizer(NP=40)
---> 16     best = algo.run(task)
     17     print(best)

/opt/conda/lib/python3.7/site-packages/NiaPy/algorithms/algorithm.py in run(self, task)
    346         try:
    347             # task.start()
--> 348             r = self.runTask(task)
    349             return r[0], r[1] * task.optType.value
    350         except (FesException, GenException, TimeException, RefException):

/opt/conda/lib/python3.7/site-packages/NiaPy/algorithms/algorithm.py in runTask(self, task)
    326         algo, xb, fxb = self.runYield(task), None, inf
    327         while not task.stopCond():
--> 328             xb, fxb = next(algo)
    329             task.nextIter()
    330         return xb, fxb

/opt/conda/lib/python3.7/site-packages/NiaPy/algorithms/algorithm.py in runYield(self, task)
    306         yield xb, fxb
    307         while True:
--> 308             pop, fpop, dparams = self.runIteration(task, pop, fpop, xb, fxb, **dparams)
    309             xb, fxb = self.getBest(pop, fpop, xb, fxb)
    310             yield xb, fxb

/opt/conda/lib/python3.7/site-packages/NiaPy/algorithms/basic/gwo.py in runIteration(self, task, pop, fpop, xb, fxb, A, A_f, B, B_f, D, D_f, **dparams)
    109                 for i, w in enumerate(pop):
    110                         A1, C1 = 2 * a * self.rand(task.D) - a, 2 * self.rand(task.D)
--> 111                         X1 = A - A1 * fabs(C1 * A - w)
    112                         A2, C2 = 2 * a * self.rand(task.D) - a, 2 * self.rand(task.D)
    113                         X2 = B - A2 * fabs(C2 * B - w)

TypeError: unsupported operand type(s) for *: 'float' and 'NoneType'

System configuration

Using docker jupyter/scipy-notebook.

[GregaVrbancic]

Hi @timzatko!

Thank you for reporting the issue. Based on the provided information I would suggest you upgrade the NiaPy to version 2.0.0rc10.

Please report back if you still facing the problem with the 2.0.0rc10 version.

[timzatko]

In 2.0.0rc10 the output for the same code is:

(None, None)
(None, None)
(None, None)
(None, None)
(None, None)

[timzatko]

Btw, then the README is incorrect as it states that the latest version is 2.0.0rc5.

[GregaVrbancic]

Thanks for the feedback, we will update the README. Regarding the issue, could you @kb2623 take a look at this?

[kb2623]

Hi to all, found the problem and solved it.

[GregaVrbancic]

Thank you @kb2623!

@timzatko feel free to try out a fixed version of NiaPy installing from git using the pip install git+https://github.com/NiaOrg/NiaPy.git command.

[GregaVrbancic]

@all-contributors add @timzatko for a bug report

[allcontributors]

@GregaVrbancic

I've put up a pull request to add @timzatko! 🎉