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# encoding=utf8 |
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import logging |
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import math |
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import numpy as np |
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from NiaPy.algorithms.algorithm import Algorithm |
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logging.basicConfig() |
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logger = logging.getLogger('NiaPy.algorithms.basic') |
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logger.setLevel('INFO') |
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__all__ = ['CatSwarmOptimization'] |
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class CatSwarmOptimization(Algorithm): |
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r"""Implementation of Cat swarm optimiization algorithm. |
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**Algorithm:** Cat swarm optimization |
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**Date:** 2019 |
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**Author:** Mihael Baketarić |
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**License:** MIT |
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**Reference paper:** Chu, S. C., Tsai, P. W., & Pan, J. S. (2006). Cat swarm optimization. In Pacific Rim international conference on artificial intelligence (pp. 854-858). Springer, Berlin, Heidelberg.. |
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""" |
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Name = ['CatSwarmOptimization', 'CSO'] |
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@staticmethod |
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def algorithmInfo(): |
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r"""Get algorithm information. |
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Returns: |
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str: Algorithm information. |
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See Also: |
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* :func:`NiaPy.algorithms.Algorithm.algorithmInfo` |
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""" |
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return r"""Chu, S. C., Tsai, P. W., & Pan, J. S. (2006). Cat swarm optimization. In Pacific Rim international conference on artificial intelligence (pp. 854-858). Springer, Berlin, Heidelberg.""" |
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@staticmethod |
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def typeParameters(): return { |
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'NP': lambda x: isinstance(x, int) and x > 0, |
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'MR': lambda x: isinstance(x, (int, float)) and 0 <= x <= 1, |
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'C1': lambda x: isinstance(x, (int, float)) and x >= 0, |
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'SMP': lambda x: isinstance(x, int) and x > 0, |
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'SPC': lambda x: isinstance(x, bool), |
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'CDC': lambda x: isinstance(x, (int, float)) and 0 <= x <= 1, |
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'SRD': lambda x: isinstance(x, (int, float)) and 0 <= x <= 1, |
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'vMax': lambda x: isinstance(x, (int, float)) and x > 0 |
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} |
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def setParameters(self, NP=30, MR=0.1, C1=2.05, SMP=3, SPC=True, CDC=0.85, SRD=0.2, vMax=1.9, **ukwargs): |
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r"""Set the algorithm parameters. |
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Arguments: |
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NP (int): Number of individuals in population. |
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MR (float): Mixture ratio. |
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C1 (float): Constant in tracing mode. |
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SMP (int): Seeking memory pool. |
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SPC (bool): Self-position considering. |
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CDC (float): Decides how many dimensions will be varied. |
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SRD (float): Seeking range of the selected dimension. |
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vMax (float): Maximal velocity. |
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See Also: |
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* :func:`NiaPy.algorithms.Algorithm.setParameters` |
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""" |
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Algorithm.setParameters(self, NP=NP, **ukwargs) |
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self.MR, self.C1, self.SMP, self.SPC, self.CDC, self.SRD, self.vMax = MR, C1, SMP, SPC, CDC, SRD, vMax |
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def initPopulation(self, task): |
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r"""Initialize population. |
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Args: |
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task (Task): Optimization task. |
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Returns: |
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Tuple[numpy.ndarray, numpy.ndarray[float], Dict[str, Any]]: |
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1. Initialized population. |
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2. Initialized populations fitness/function values. |
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3. Additional arguments: |
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* Dictionary of modes (seek or trace) and velocities for each cat |
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See Also: |
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* :func:`NiaPy.algorithms.Algorithm.initPopulation` |
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""" |
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pop, fpop, d = Algorithm.initPopulation(self, task) |
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d['modes'] = self.randomSeekTrace() |
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d['velocities'] = self.uniform(-self.vMax, self.vMax, [len(pop), task.D]) |
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return pop, fpop, d |
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def repair(self, x, l, u): |
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r"""Repair array to range. |
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Args: |
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x (numpy.ndarray): Array to repair. |
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l (numpy.ndarray): Lower limit of allowed range. |
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u (numpy.ndarray): Upper limit of allowed range. |
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Returns: |
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numpy.ndarray: Repaired array. |
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""" |
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ir = np.where(x < l) |
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x[ir] = l[ir] |
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ir = np.where(x > u) |
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x[ir] = u[ir] |
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return x |
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def randomSeekTrace(self): |
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r"""Set cats into seeking/tracing mode. |
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Returns: |
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numpy.ndarray: One or zero. One means tracing mode. Zero means seeking mode. Length of list is equal to NP. |
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""" |
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lista = np.zeros((self.NP,), dtype=int) |
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indexes = np.arange(self.NP) |
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self.Rand.shuffle(indexes) |
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lista[indexes[:int(self.NP * self.MR)]] = 1 |
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return lista |
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def weightedSelection(self, weights): |
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r"""Random selection considering the weights. |
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Args: |
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weights (numpy.ndarray): weight for each potential position. |
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Returns: |
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int: index of selected next position. |
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""" |
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cumulative_sum = np.cumsum(weights) |
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return np.argmax(cumulative_sum >= (self.rand() * cumulative_sum[-1])) |
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def seekingMode(self, task, cat, fcat, pop, fpop, fxb): |
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r"""Seeking mode. |
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Args: |
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task (Task): Optimization task. |
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cat (numpy.ndarray): Individual from population. |
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fcat (float): Current individual's fitness/function value. |
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pop (numpy.ndarray): Current population. |
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fpop (numpy.ndarray): Current population fitness/function values. |
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fxb (float): Current best cat fitness/function value. |
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Returns: |
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Tuple[numpy.ndarray, float, numpy.ndarray, float]: |
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1. Updated individual's position |
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2. Updated individual's fitness/function value |
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3. Updated global best position |
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4. Updated global best fitness/function value |
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""" |
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cat_copies = [] |
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cat_copies_fs = [] |
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for j in range(self.SMP - 1 if self.SPC else self.SMP): |
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cat_copies.append(cat.copy()) |
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indexes = np.arange(task.D) |
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self.Rand.shuffle(indexes) |
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to_vary_indexes = indexes[:int(task.D * self.CDC)] |
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if self.randint(2) == 1: |
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cat_copies[j][to_vary_indexes] += cat_copies[j][to_vary_indexes] * self.SRD |
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else: |
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cat_copies[j][to_vary_indexes] -= cat_copies[j][to_vary_indexes] * self.SRD |
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cat_copies[j] = task.repair(cat_copies[j]) |
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cat_copies_fs.append(task.eval(cat_copies[j])) |
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if self.SPC: |
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cat_copies.append(cat.copy()) |
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cat_copies_fs.append(fcat) |
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cat_copies_select_probs = np.ones(len(cat_copies)) |
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fmax = np.max(cat_copies_fs) |
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fmin = np.min(cat_copies_fs) |
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if any(x != cat_copies_fs[0] for x in cat_copies_fs): |
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fb = fmax |
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if math.isinf(fb): |
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cat_copies_select_probs = np.full(len(cat_copies), fb) |
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else: |
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cat_copies_select_probs = np.abs(cat_copies_fs - fb) / (fmax - fmin) |
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if fmin < fxb: |
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fxb = fmin |
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ind = self.randint(self.NP, 1, 0) |
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pop[ind] = cat_copies[np.where(cat_copies_fs == fmin)[0][0]] |
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fpop[ind] = fmin |
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sel_index = self.weightedSelection(cat_copies_select_probs) |
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return cat_copies[sel_index], cat_copies_fs[sel_index], pop, fpop |
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def tracingMode(self, task, cat, velocity, xb): |
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r"""Tracing mode. |
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Args: |
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task (Task): Optimization task. |
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cat (numpy.ndarray): Individual from population. |
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velocity (numpy.ndarray): Velocity of individual. |
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xb (numpy.ndarray): Current best individual. |
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Returns: |
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Tuple[numpy.ndarray, float, numpy.ndarray]: |
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1. Updated individual's position |
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2. Updated individual's fitness/function value |
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3. Updated individual's velocity vector |
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""" |
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Vnew = self.repair(velocity + (self.uniform(0, 1, len(velocity)) * self.C1 * (xb - cat)), np.full(task.D, -self.vMax), np.full(task.D, self.vMax)) |
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cat_new = task.repair(cat + Vnew) |
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return cat_new, task.eval(cat_new), Vnew |
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def runIteration(self, task, pop, fpop, xb, fxb, velocities, modes, **dparams): |
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r"""Core function of Cat Swarm Optimization algorithm. |
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Args: |
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task (Task): Optimization task. |
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pop (numpy.ndarray): Current population. |
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fpop (numpy.ndarray): Current population fitness/function values. |
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xb (numpy.ndarray): Current best individual. |
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fxb (float): Current best cat fitness/function value. |
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velocities (numpy.ndarray): Velocities of individuals. |
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modes (numpy.ndarray): Flag of each individual. |
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**dparams (Dict[str, Any]): Additional function arguments. |
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Returns: |
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Tuple[numpy.ndarray, numpy.ndarray, numpy.ndarray, float, Dict[str, Any]]: |
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1. New population. |
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2. New population fitness/function values. |
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3. New global best solution. |
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4. New global best solutions fitness/objective value. |
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5. Additional arguments: |
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* Dictionary of modes (seek or trace) and velocities for each cat. |
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""" |
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pop_copies = pop.copy() |
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for k in range(len(pop_copies)): |
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if modes[k] == 0: |
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pop_copies[k], fpop[k], pop_copies[:], fpop[:] = self.seekingMode(task, pop_copies[k], fpop[k], pop_copies, fpop, fxb) |
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else: # if cat in tracing mode |
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pop_copies[k], fpop[k], velocities[k] = self.tracingMode(task, pop_copies[k], velocities[k], xb) |
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ib = np.argmin(fpop) |
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if fpop[ib] < fxb: xb, fxb = pop_copies[ib].copy(), fpop[ib] |
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return pop_copies, fpop, xb, fxb, {'velocities': velocities, 'modes': self.randomSeekTrace()} |
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# vim: tabstop=3 noexpandtab shiftwidth=3 softtabstop=3 |
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