Create plot_evolution.py

tutorials/plot_evolution.py

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+from pypop7.benchmarks.utils import generate_xyz
+import numpy as np
+import matplotlib.pyplot as plt  # for static plotting
+
+from pypop7.optimizers.es.es import ES  # abstract class for all evolution Strategies
+from pypop7.optimizers.es.maes import MAES  # Matrix Adaptation Evolution Strategy
+
+
+def cd(x):  # from https://arxiv.org/pdf/1610.00040v1.pdf
+    return 7.0 * (x[0] ** 2) + 6.0 * x[0] * x[1] + 8.0 * (x[1] ** 2)
+
+
+# helper function for 2D-plotting
+def plot_contour(func, x, y, levels=None, num=200):
+    """Plot a 2D contour of the fitness landscape.
+
+    Parameters
+    ----------
+    func    : func
+              benchmarking function.
+    x       : list
+              x-axis range.
+    y       : list
+              y-axis range.
+    levels  : int
+              number of contour lines.
+    num     : int
+              number of samples in each of x- and y-axis range.
+    is_save : bool
+              whether or not to save the generated figure in the *local* folder.
+
+    Returns
+    -------
+    An online figure.
+    """
+    x, y, z = generate_xyz(func, x, y, num)
+    if levels is None:
+        plt.contourf(x, y, z, cmap='bone')
+        plt.contour(x, y, z)
+    else:
+        plt.contourf(x, y, z, levels, cmap='cool')
+        c = plt.contour(x, y, z, levels, colors='k')
+        plt.clabel(c, inline=True, fontsize=12, colors='white')
+    plt.xlabel('x')
+    plt.ylabel('y')
+
+plt.rcParams['font.family'] = 'Times New Roman'
+plt.rcParams['font.size'] = 10
+
+
+def plot(xs, means):
+    for i in range(len(xs)):
+        sub_figure = '_' + str(i) + '.png'
+
+        # set title
+        plt.title("cd")
+
+        # set boundary
+        plt.xlim(-10, 10)
+        plt.ylim(-10, 10)
+
+        # draw contour and points
+        plot_contour(cd, [-10.0, 10.0], [-10.0, 10.0])
+        plt.scatter(xs[i][:, 0], xs[i][:, 1], color='green')
+        plt.scatter(means[i][0], means[i][1], color='m')
+
+        # save and show figure
+        plt.savefig(sub_figure, dpi=300)
+        plt.show()
+
+
+# <3> - Extend Optimizer Class MAES to Generate Data for Plotting
+class MAESPLOT(MAES):  # to overwrite original MAES algorithm for plotting
+    def optimize(self, fitness_function=None, args=None):  # for all generations (iterations)
+        fitness = ES.optimize(self, fitness_function)
+        z, d, mean, s, tm, y = self.initialize()
+        print(z)
+        # print(z+mean)
+        xs = []  # for plotting
+        means = []
+
+        while not self._check_terminations():
+            z, d, y = self.iterate(z, d, mean, tm, y, args)
+            # print(z+mean)
+            if self.saving_fitness and (not self._n_generations % self.saving_fitness):
+                xs.append(self.sigma*d+mean)  # for plotting
+                means.append(mean.copy())
+            mean, s, tm = self._update_distribution(z, d, mean, s, tm, y)
+            self._print_verbose_info(fitness, y)
+            self._n_generations += 1
+            if self.is_restart:
+                z, d, mean, s, tm, y = self.restart_reinitialize(z, d, mean, s, tm, y)
+        res = self._collect(fitness, y, mean)
+        res['xs'] = xs  # for plotting
+        return xs, means
+
+
+if __name__ == '__main__':
+    ndim_problem = 2  # dimension of objective function
+    problem = {'fitness_function': cd,  # objective (fitness) function
+               'ndim_problem': ndim_problem,  # number of dimensionality of objective function
+               'lower_boundary': -10.0*np.ones((ndim_problem,)),  # lower boundary of search range
+               'upper_boundary': 10.0*np.ones((ndim_problem,))}  # upper boundary of search range
+    options = {'max_function_evaluations': 3e3,  # maximum of function evaluations
+               'n_individuals': 200,
+               'seed_rng': 2022,  # seed of random number generation (for repeatability)
+               'x': (7.0, -7.0),
+               'sigma': 0.05,  # global step-size of Gaussian search distribution (not necessarily an optimal value)
+               'saving_fitness': 4,  # to record best-so-far fitness every 50 function evaluations
+               'is_restart': False}  # whether or not to run the (default) restart process
+    xs, means = MAESPLOT(problem, options).optimize()
+    plot(xs, means)