added schaffer2 function

added output for improvement of fitness
added CMAES algorithm, that requires further testing

main.py

@@ -0,0 +1,43 @@
+import functions
+import numpy as np
+import solvers
+
+from matplotlib import pyplot as plt
+
+
+def main():
+    plot_rest = True
+    f = functions.Rastrigin()
+    # f = functions.Sphere()
+    # s = solvers.SimpleEvolutionStrategy(f, np.array([2, 2]))
+    s = solvers.CMAEvolutionStrategy(f, np.array([2.0, 2.0]), np.array([[2.0, 0.0], [0.0, 2.0]]))
+    old_fitness = 100
+    fitness = old_fitness * 0.9
+    old = None
+    plt.set_cmap('Spectral')
+
+    while abs(old_fitness - fitness) > 0.001:
+        old_fitness = fitness
+        samples = s.sample(2000)
+        elite, fitness = s.rank(samples, 150)
+        s.update(elite)
+
+        if plot_rest:
+            rest = np.setdiff1d(samples, elite, assume_unique=True)
+            rest = rest.reshape((int(rest.shape[0]/2), 2))
+        plt.pcolormesh(*f.grid())
+        if plot_rest:
+            plt.scatter(*rest.transpose(), color="dimgrey")
+        if old is not None:
+            plt.scatter(*old.transpose(), color="orange")
+        plt.scatter(*elite.transpose(), color="yellow")
+        # plt.scatter(*elite[0].transpose(), color="green")
+        print('old fitness: {}\nnew fitness: {}\nimprovement: {}\n'.format(old_fitness, fitness,
+            old_fitness - fitness))
+        plt.show()
+        old = elite 
+
+
+if __name__ == '__main__':
+    main()
+