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50  <h1>Source code for park.diffev</h1><div class="highlight"><pre>
51<span class="kn">from</span> <span class="nn">random</span> <span class="kn">import</span> <span class="n">randint</span><span class="p">,</span> <span class="n">random</span>
52<span class="kn">import</span> <span class="nn">numpy</span>
53
54<div class="viewcode-block" id="DE"><a class="viewcode-back" href="../../dev/api/park.html#park.diffev.DE">[docs]</a><span class="k">class</span> <span class="nc">DE</span><span class="p">:</span>
55    <span class="sd">&quot;&quot;&quot;</span>
56<span class="sd">    Differential evolution test implementation</span>
57<span class="sd">    Implements the Scheme_DE_rand_1 variant</span>
58
59<span class="sd">       F: float</span>
60<span class="sd">           weighting factor which determines the magnitude of perturbation</span>
61<span class="sd">           occurring in each generation.</span>
62
63<span class="sd">       crossover_rate:  float</span>
64<span class="sd">           In general, 0 &lt; crossover_rate &lt; 1.  Usually</span>
65<span class="sd">           considerably lower than 1.  Convergence slows as the value</span>
66<span class="sd">           increases, but higher crossover rates may be necessary when</span>
67
68<span class="sd">       func: w = f(p)</span>
69<span class="sd">           The function to be minimized, of the form w = f(p), where p</span>
70<span class="sd">           is a vector of length func_dim and w is a scalar</span>
71
72<span class="sd">       func_dim: int</span>
73<span class="sd">           The dimension of the objective function</span>
74
75<span class="sd">       pop: array</span>
76<span class="sd">           The initial population.  This should be an iterable composed of</span>
77<span class="sd">           Rank-1 numpy arrays.  The population size must be at least 4,</span>
78<span class="sd">           preferably much greater.</span>
79
80<span class="sd">       l_bound, u_bound: vector</span>
81<span class="sd">           arrays of size func_dim representing the upper and lower bounds</span>
82<span class="sd">           for the parameters in the solution vectors</span>
83
84<span class="sd">       tol: float</span>
85<span class="sd">           if (max(pop_values) - min(pop_values) &lt;= conv), the population</span>
86<span class="sd">           has converged and the evolution will stop</span>
87<span class="sd">       &quot;&quot;&quot;</span>
88
89    <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">F</span><span class="p">,</span> <span class="n">crossover_rate</span><span class="p">,</span> <span class="n">func</span><span class="p">,</span> <span class="n">func_dim</span><span class="p">,</span> <span class="n">pop</span><span class="p">,</span> <span class="n">l_bound</span><span class="p">,</span>
90                 <span class="n">u_bound</span><span class="p">,</span> <span class="n">tol</span><span class="o">=</span><span class="mf">1e-7</span><span class="p">):</span>
91        <span class="bp">self</span><span class="o">.</span><span class="n">pop_size</span>          <span class="o">=</span> <span class="nb">len</span><span class="p">(</span><span class="n">pop</span><span class="p">)</span>
92        <span class="bp">self</span><span class="o">.</span><span class="n">dimension</span>         <span class="o">=</span> <span class="n">func_dim</span>
93        <span class="bp">self</span><span class="o">.</span><span class="n">F_orig</span>            <span class="o">=</span> <span class="n">F</span>
94        <span class="bp">self</span><span class="o">.</span><span class="n">F</span>                 <span class="o">=</span> <span class="n">F</span>
95        <span class="bp">self</span><span class="o">.</span><span class="n">crossover_rate</span>    <span class="o">=</span> <span class="n">crossover_rate</span>
96        <span class="bp">self</span><span class="o">.</span><span class="n">func</span>              <span class="o">=</span> <span class="n">func</span>
97        <span class="bp">self</span><span class="o">.</span><span class="n">tol</span>               <span class="o">=</span> <span class="n">tol</span>
98        <span class="bp">self</span><span class="o">.</span><span class="n">l_bound</span>           <span class="o">=</span> <span class="n">l_bound</span>
99        <span class="bp">self</span><span class="o">.</span><span class="n">u_bound</span>           <span class="o">=</span> <span class="n">u_bound</span>
100        <span class="bp">self</span><span class="o">.</span><span class="n">population</span>        <span class="o">=</span> <span class="n">pop</span>
101        <span class="bp">self</span><span class="o">.</span><span class="n">generations</span>       <span class="o">=</span> <span class="mi">0</span>
102        <span class="bp">self</span><span class="o">.</span><span class="n">pop_values</span>        <span class="o">=</span> <span class="p">[</span><span class="bp">self</span><span class="o">.</span><span class="n">func</span><span class="p">(</span><span class="n">p</span><span class="p">)</span> <span class="k">for</span> <span class="n">p</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">population</span><span class="p">]</span>
103        <span class="bp">self</span><span class="o">.</span><span class="n">best_gene</span><span class="p">,</span><span class="bp">self</span><span class="o">.</span><span class="n">best_value</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">get_best_gene</span><span class="p">()</span>
104        <span class="bp">self</span><span class="o">.</span><span class="n">best_gene_history</span> <span class="o">=</span> <span class="p">[</span><span class="bp">self</span><span class="o">.</span><span class="n">best_gene</span><span class="p">]</span>
105        <span class="bp">self</span><span class="o">.</span><span class="n">best_val_history</span>  <span class="o">=</span> <span class="p">[</span><span class="bp">self</span><span class="o">.</span><span class="n">best_value</span><span class="p">]</span>
106        <span class="bp">self</span><span class="o">.</span><span class="n">ncalls</span>            <span class="o">=</span> <span class="mi">0</span>
107
108    <span class="c">#//////////////////////////////////////////////////</span>
109<div class="viewcode-block" id="DE.evolve"><a class="viewcode-back" href="../../dev/api/park.html#park.diffev.DE.evolve">[docs]</a>    <span class="k">def</span> <span class="nf">evolve</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">numgens</span><span class="o">=</span><span class="mi">1000</span><span class="p">,</span> <span class="n">monitor</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
110        <span class="sd">&#39;&#39;&#39;Evolve the population for numgens generations, or until it converges.</span>
111<span class="sd">            Returns the best vector from the run&#39;&#39;&#39;</span>
112        <span class="k">try</span><span class="p">:</span>
113            <span class="kn">import</span> <span class="nn">psyco</span>
114            <span class="n">psyco</span><span class="o">.</span><span class="n">full</span><span class="p">()</span>
115        <span class="k">except</span> <span class="ne">ImportError</span><span class="p">:</span>
116            <span class="k">pass</span>
117
118        <span class="n">start_gen</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">generations</span>
119        <span class="k">for</span> <span class="n">gen</span> <span class="ow">in</span> <span class="nb">xrange</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">generations</span> <span class="o">+</span> <span class="mi">1</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">generations</span> <span class="o">+</span> <span class="n">numgens</span> <span class="o">+</span> <span class="mi">1</span><span class="p">):</span>
120            <span class="n">candidate_pop</span> <span class="o">=</span> <span class="p">[]</span>
121
122            <span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="nb">xrange</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">pop_size</span><span class="p">):</span>
123                <span class="p">(</span><span class="n">r1</span><span class="p">,</span> <span class="n">r2</span><span class="p">,</span> <span class="n">r3</span><span class="p">)</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">select_participants</span><span class="p">(</span><span class="n">i</span><span class="p">)</span>
124
125                <span class="c">#perturbation/mutation</span>
126                <span class="n">candidate</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">population</span><span class="p">[</span><span class="n">r1</span><span class="p">]</span> <span class="o">+</span> <span class="bp">self</span><span class="o">.</span><span class="n">F</span><span class="o">*</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">population</span><span class="p">[</span><span class="n">r2</span><span class="p">]</span>
127                                                          <span class="o">-</span> <span class="bp">self</span><span class="o">.</span><span class="n">population</span><span class="p">[</span><span class="n">r3</span><span class="p">])</span>
128
129                <span class="c">#crossover</span>
130                <span class="n">candidate</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">crossover</span><span class="p">(</span><span class="n">candidate</span><span class="p">,</span> <span class="n">i</span><span class="p">)</span>
131
132                <span class="c">#check bound constraints</span>
133                <span class="k">if</span> <span class="ow">not</span> <span class="bp">self</span><span class="o">.</span><span class="n">is_within_bounds</span><span class="p">(</span><span class="n">candidate</span><span class="p">):</span>
134                    <span class="n">candidate</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">get_random_gene</span><span class="p">()</span>
135
136                <span class="c">#test fitness to determine membership in next gen</span>
137                <span class="n">candidate_val</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">func</span><span class="p">(</span><span class="n">candidate</span><span class="p">)</span>
138                <span class="k">if</span> <span class="n">candidate_val</span> <span class="o">&lt;</span> <span class="bp">self</span><span class="o">.</span><span class="n">pop_values</span><span class="p">[</span><span class="n">i</span><span class="p">]:</span>
139                    <span class="n">candidate_pop</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">candidate</span><span class="p">)</span>
140                    <span class="bp">self</span><span class="o">.</span><span class="n">pop_values</span><span class="p">[</span><span class="n">i</span><span class="p">]</span> <span class="o">=</span> <span class="nb">float</span><span class="p">(</span><span class="n">candidate_val</span><span class="p">)</span>
141                <span class="k">else</span><span class="p">:</span>
142                    <span class="n">candidate_pop</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">population</span><span class="p">[</span><span class="n">i</span><span class="p">])</span>
143            <span class="bp">self</span><span class="o">.</span><span class="n">ncalls</span> <span class="o">+=</span> <span class="bp">self</span><span class="o">.</span><span class="n">pop_size</span>
144
145            <span class="bp">self</span><span class="o">.</span><span class="n">population</span>  <span class="o">=</span> <span class="n">candidate_pop</span>
146            <span class="n">x</span><span class="p">,</span><span class="n">fx</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">get_best_gene</span><span class="p">()</span>
147            <span class="k">if</span> <span class="n">fx</span> <span class="o">&lt;</span> <span class="bp">self</span><span class="o">.</span><span class="n">best_value</span><span class="p">:</span>
148                <span class="bp">self</span><span class="o">.</span><span class="n">best_gene</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">best_value</span> <span class="o">=</span> <span class="n">x</span><span class="p">,</span><span class="n">fx</span>
149                <span class="k">if</span> <span class="n">monitor</span> <span class="ow">is</span> <span class="ow">not</span> <span class="bp">None</span><span class="p">:</span>
150                    <span class="n">monitor</span><span class="o">.</span><span class="n">improvement</span><span class="p">(</span><span class="n">x</span><span class="p">,</span><span class="n">fx</span><span class="p">,</span><span class="bp">self</span><span class="o">.</span><span class="n">ncalls</span><span class="p">)</span>
151            <span class="bp">self</span><span class="o">.</span><span class="n">best_val_history</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">best_value</span><span class="p">)</span>
152            <span class="bp">self</span><span class="o">.</span><span class="n">best_gene_history</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">best_gene</span><span class="p">)</span>
153            <span class="bp">self</span><span class="o">.</span><span class="n">generations</span> <span class="o">=</span> <span class="n">gen</span>
154
155            <span class="k">if</span> <span class="n">monitor</span> <span class="ow">is</span> <span class="ow">not</span> <span class="bp">None</span><span class="p">:</span>
156                <span class="n">monitor</span><span class="o">.</span><span class="n">progress</span><span class="p">(</span><span class="n">gen</span><span class="o">-</span><span class="n">start_gen</span><span class="p">,</span><span class="n">numgens</span><span class="p">)</span>
157
158            <span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">is_converged</span><span class="p">():</span>
159                <span class="k">break</span>
160
161        <span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">best_gene</span>
162
163
164    <span class="c">#////////////////////////////////////////////////</span></div>
165<div class="viewcode-block" id="DE.get_random_gene"><a class="viewcode-back" href="../../dev/api/park.html#park.diffev.DE.get_random_gene">[docs]</a>    <span class="k">def</span> <span class="nf">get_random_gene</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
166        <span class="sd">&#39;&#39;&#39;Generate a random gene within the bounds constraints.</span>
167<span class="sd">           Used to replace out-of-bounds genes&#39;&#39;&#39;</span>
168        <span class="n">result</span> <span class="o">=</span> <span class="p">[</span><span class="n">numpy</span><span class="o">.</span><span class="n">random</span><span class="o">.</span><span class="n">uniform</span><span class="p">(</span><span class="n">low</span><span class="p">,</span> <span class="n">high</span><span class="p">)</span>
169                  <span class="k">for</span> <span class="n">low</span><span class="p">,</span> <span class="n">high</span> <span class="ow">in</span> <span class="nb">zip</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">l_bound</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">u_bound</span><span class="p">)]</span>
170        <span class="k">return</span> <span class="n">numpy</span><span class="o">.</span><span class="n">array</span><span class="p">(</span><span class="n">result</span><span class="p">)</span>
171
172    <span class="c">#////////////////////////////////////////////////</span></div>
173<div class="viewcode-block" id="DE.is_within_bounds"><a class="viewcode-back" href="../../dev/api/park.html#park.diffev.DE.is_within_bounds">[docs]</a>    <span class="k">def</span> <span class="nf">is_within_bounds</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">gene</span><span class="p">):</span>
174        <span class="sd">&#39;&#39;&#39;Determine whether the gene meets the bounds constraints&#39;&#39;&#39;</span>
175        <span class="k">return</span> <span class="n">numpy</span><span class="o">.</span><span class="n">all</span><span class="p">(</span> <span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">l_bound</span> <span class="o">&lt;</span> <span class="n">gene</span><span class="p">)</span> <span class="o">&amp;</span> <span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">u_bound</span> <span class="o">&gt;</span> <span class="n">gene</span><span class="p">)</span> <span class="p">)</span>
176
177    <span class="c">#////////////////////////////////////////////////</span>
178    <span class="c">#This appears to be a total failure.  I&#39;ll leave the code in,</span>
179    <span class="c">#but it&#39;s not called from the main evolution loop anymore.</span></div>
180<div class="viewcode-block" id="DE.adjust_F"><a class="viewcode-back" href="../../dev/api/park.html#park.diffev.DE.adjust_F">[docs]</a>    <span class="k">def</span> <span class="nf">adjust_F</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
181        <span class="sd">&#39;&#39;&#39;Adjust F to account for stagnation of the population &#39;&#39;&#39;</span>
182        <span class="c">#has the best vector improved this generation?</span>
183        <span class="n">idx</span> <span class="o">=</span> <span class="nb">len</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">best_val_history</span><span class="p">)</span>
184        <span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">best_val_history</span><span class="p">[</span><span class="n">idx</span> <span class="o">-</span> <span class="mi">1</span><span class="p">]</span> <span class="o">==</span> <span class="bp">self</span><span class="o">.</span><span class="n">best_val_history</span><span class="p">[</span><span class="n">idx</span> <span class="o">-</span> <span class="mi">2</span><span class="p">]:</span>
185            <span class="bp">self</span><span class="o">.</span><span class="n">stagnant_gens</span> <span class="o">+=</span> <span class="mi">1</span>
186        <span class="k">else</span><span class="p">:</span>
187            <span class="bp">self</span><span class="o">.</span><span class="n">stagnant_gens</span>  <span class="o">=</span> <span class="mi">0</span>
188
189        <span class="c">#adapt F to account for stagnation</span>
190        <span class="bp">self</span><span class="o">.</span><span class="n">F</span> <span class="o">=</span> <span class="nb">min</span><span class="p">(</span> <span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">F_orig</span> <span class="o">+</span> <span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">stagnant_gens</span> <span class="o">*</span> <span class="mf">0.01</span><span class="p">)),</span> <span class="mf">2.0</span><span class="p">)</span>
191
192    <span class="c">#////////////////////////////////////////////////</span></div>
193<div class="viewcode-block" id="DE.get_best_gene"><a class="viewcode-back" href="../../dev/api/park.html#park.diffev.DE.get_best_gene">[docs]</a>    <span class="k">def</span> <span class="nf">get_best_gene</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
194        <span class="sd">&#39;&#39;&#39;find the most fit gene in the current population&#39;&#39;&#39;</span>
195        <span class="c">#print &quot;pop&quot;, self.pop_values</span>
196
197        <span class="n">best_index</span> <span class="o">=</span> <span class="n">numpy</span><span class="o">.</span><span class="n">argmin</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">pop_values</span><span class="p">)</span>
198        <span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">population</span><span class="p">[</span><span class="n">best_index</span><span class="p">],</span><span class="bp">self</span><span class="o">.</span><span class="n">pop_values</span><span class="p">[</span><span class="n">best_index</span><span class="p">],</span>
199
200    <span class="c">#////////////////////////////////////////////////</span></div>
201<div class="viewcode-block" id="DE.select_participants"><a class="viewcode-back" href="../../dev/api/park.html#park.diffev.DE.select_participants">[docs]</a>    <span class="k">def</span> <span class="nf">select_participants</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">i</span><span class="p">):</span>
202        <span class="sd">&#39;&#39;&#39;generate r1, r2, and r3 randomly from the range [0, NP-1]</span>
203<span class="sd">            such that they are distinct values not equal to i&#39;&#39;&#39;</span>
204        <span class="n">choices</span> <span class="o">=</span> <span class="p">[</span><span class="n">i</span><span class="p">]</span>
205        <span class="k">for</span> <span class="n">choice</span> <span class="ow">in</span> <span class="nb">xrange</span><span class="p">(</span><span class="mi">3</span><span class="p">):</span>
206            <span class="k">while</span> <span class="bp">True</span><span class="p">:</span>
207                <span class="n">j</span> <span class="o">=</span> <span class="n">numpy</span><span class="o">.</span><span class="n">random</span><span class="o">.</span><span class="n">randint</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">pop_size</span><span class="o">-</span><span class="mi">1</span><span class="p">)</span>
208                <span class="k">if</span> <span class="n">j</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">choices</span><span class="p">:</span>
209                    <span class="k">break</span>
210            <span class="n">choices</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">j</span><span class="p">)</span>
211        <span class="k">return</span> <span class="n">choices</span><span class="p">[</span><span class="mi">1</span><span class="p">:]</span>
212    <span class="c">#////////////////////////////////////////////////</span></div>
213<div class="viewcode-block" id="DE.crossover"><a class="viewcode-back" href="../../dev/api/park.html#park.diffev.DE.crossover">[docs]</a>    <span class="k">def</span> <span class="nf">crossover</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">candidate</span><span class="p">,</span> <span class="n">i</span><span class="p">):</span>
214        <span class="sd">&#39;&#39;&#39;Perform a crossover between the candidate and the ith member of</span>
215<span class="sd">            the previous generation.&#39;&#39;&#39;</span>
216        <span class="n">result</span> <span class="o">=</span> <span class="p">[]</span>
217
218        <span class="c">#generate lower bound of crossover (this bound is inclusive)</span>
219        <span class="n">low</span> <span class="o">=</span> <span class="n">randint</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">dimension</span><span class="o">-</span><span class="mi">1</span><span class="p">)</span>
220
221        <span class="c">#determine the size of the crossover</span>
222        <span class="n">L</span> <span class="o">=</span> <span class="mi">0</span>
223        <span class="k">while</span> <span class="n">random</span><span class="p">()</span> <span class="o">&lt;</span> <span class="bp">self</span><span class="o">.</span><span class="n">crossover_rate</span> <span class="ow">and</span> <span class="n">L</span> <span class="o">&lt;</span> <span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">dimension</span> <span class="o">-</span> <span class="n">low</span><span class="p">):</span>
224            <span class="n">L</span> <span class="o">+=</span> <span class="mi">1</span>
225
226        <span class="c">#calculate the upper bound of crossover (this bound is exclusive)</span>
227        <span class="n">high</span> <span class="o">=</span> <span class="n">low</span> <span class="o">+</span> <span class="n">L</span>
228
229        <span class="n">high</span>  <span class="o">=</span> <span class="n">numpy</span><span class="o">.</span><span class="n">repeat</span><span class="p">(</span><span class="n">high</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">dimension</span><span class="p">)</span>
230        <span class="n">low</span>   <span class="o">=</span> <span class="n">numpy</span><span class="o">.</span><span class="n">repeat</span><span class="p">(</span><span class="n">low</span><span class="p">,</span>  <span class="bp">self</span><span class="o">.</span><span class="n">dimension</span><span class="p">)</span>
231        <span class="n">seq</span>   <span class="o">=</span> <span class="n">numpy</span><span class="o">.</span><span class="n">arange</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">dimension</span><span class="p">)</span>
232
233        <span class="n">result</span> <span class="o">=</span> <span class="n">numpy</span><span class="o">.</span><span class="n">choose</span><span class="p">(</span> <span class="p">((</span><span class="n">seq</span> <span class="o">&gt;=</span> <span class="n">low</span><span class="p">)</span><span class="o">&amp;</span><span class="p">(</span><span class="n">seq</span> <span class="o">&lt;</span> <span class="n">high</span><span class="p">)),</span>
234                             <span class="p">[</span><span class="n">candidate</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">population</span><span class="p">[</span><span class="n">i</span><span class="p">]]</span> <span class="p">)</span>
235        <span class="k">return</span> <span class="n">result</span>
236</div>
237<div class="viewcode-block" id="DE.is_converged"><a class="viewcode-back" href="../../dev/api/park.html#park.diffev.DE.is_converged">[docs]</a>    <span class="k">def</span> <span class="nf">is_converged</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
238        <span class="sd">&#39;&#39;&#39;check for convergence&#39;&#39;&#39;</span>
239        <span class="k">return</span> <span class="nb">max</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">pop_values</span><span class="p">)</span> <span class="o">-</span> <span class="nb">min</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">pop_values</span><span class="p">)</span> <span class="o">&lt;=</span> <span class="bp">self</span><span class="o">.</span><span class="n">tol</span>
240</div></div>
241<div class="viewcode-block" id="diffev"><a class="viewcode-back" href="../../dev/api/park.html#park.diffev.diffev">[docs]</a><span class="k">def</span> <span class="nf">diffev</span><span class="p">(</span><span class="n">fn</span><span class="p">,</span> <span class="n">bounds</span><span class="p">,</span> <span class="n">x0</span><span class="o">=</span><span class="bp">None</span><span class="p">,</span> <span class="n">pop_scale</span><span class="o">=</span><span class="mi">4</span><span class="p">,</span> <span class="n">crossover_rate</span><span class="o">=</span><span class="mf">0.8</span><span class="p">,</span>
242           <span class="n">Fscale</span><span class="o">=</span><span class="mi">1</span><span class="p">,</span> <span class="n">tolerance</span><span class="o">=</span><span class="mf">1e-5</span><span class="p">,</span> <span class="n">maxiter</span><span class="o">=</span><span class="mi">1000</span><span class="p">,</span> <span class="n">monitor</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
243    <span class="sd">&quot;&quot;&quot;</span>
244<span class="sd">    Run differential evolution, returning x,fx,ncalls</span>
245<span class="sd">    &quot;&quot;&quot;</span>
246    <span class="n">lo</span><span class="p">,</span> <span class="n">hi</span> <span class="o">=</span> <span class="n">numpy</span><span class="o">.</span><span class="n">asarray</span><span class="p">(</span><span class="n">bounds</span><span class="p">[</span><span class="mi">0</span><span class="p">]),</span> <span class="n">numpy</span><span class="o">.</span><span class="n">asarray</span><span class="p">(</span><span class="n">bounds</span><span class="p">[</span><span class="mi">1</span><span class="p">])</span>
247    <span class="n">dim</span> <span class="o">=</span> <span class="nb">len</span><span class="p">(</span><span class="n">lo</span><span class="p">)</span>
248    <span class="n">pop</span> <span class="o">=</span> <span class="n">gen_pop</span><span class="p">(</span><span class="n">dim</span><span class="o">*</span><span class="n">pop_scale</span><span class="p">,</span> <span class="n">lo</span><span class="p">,</span> <span class="n">hi</span><span class="p">,</span> <span class="n">dim</span><span class="p">)</span>
249    <span class="k">if</span> <span class="n">x0</span> <span class="ow">is</span> <span class="ow">not</span> <span class="bp">None</span><span class="p">:</span>
250        <span class="n">pop</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="o">=</span> <span class="n">numpy</span><span class="o">.</span><span class="n">asarray</span><span class="p">(</span><span class="n">x0</span><span class="p">)</span>
251    <span class="n">evolver</span> <span class="o">=</span> <span class="n">DE</span><span class="p">(</span><span class="n">Fscale</span><span class="p">,</span> <span class="n">crossover_rate</span><span class="p">,</span> <span class="n">fn</span><span class="p">,</span> <span class="n">dim</span><span class="p">,</span> <span class="n">pop</span><span class="p">,</span> <span class="n">lo</span><span class="p">,</span> <span class="n">hi</span><span class="p">,</span> <span class="n">tolerance</span><span class="p">)</span>
252    <span class="n">evolver</span><span class="o">.</span><span class="n">evolve</span><span class="p">(</span><span class="n">maxiter</span><span class="p">,</span> <span class="n">monitor</span><span class="o">=</span><span class="n">monitor</span><span class="p">)</span>
253    <span class="k">return</span> <span class="n">evolver</span><span class="o">.</span><span class="n">best_gene</span><span class="p">,</span> <span class="n">evolver</span><span class="o">.</span><span class="n">best_value</span><span class="p">,</span> <span class="n">evolver</span><span class="o">.</span><span class="n">ncalls</span>
254
255
256
257
258<span class="c">########################################################################</span>
259<span class="c">#end DE def</span>
260<span class="c">########################################################################</span></div>
261<div class="viewcode-block" id="gen_pop"><a class="viewcode-back" href="../../dev/api/park.html#park.diffev.gen_pop">[docs]</a><span class="k">def</span> <span class="nf">gen_pop</span><span class="p">(</span><span class="n">size</span><span class="p">,</span> <span class="n">l_bound</span><span class="p">,</span> <span class="n">u_bound</span><span class="p">,</span> <span class="n">dimension</span><span class="p">):</span>
262    <span class="sd">&#39;&#39;&#39;generate a random population of vectors within the given bounds.  dimension</span>
263<span class="sd">       indicates the length of the vectors.  l_bound and u_bound should be vectors</span>
264<span class="sd">       of length dimension (any iterable container should work)&#39;&#39;&#39;</span>
265    <span class="n">result</span> <span class="o">=</span> <span class="p">[]</span>
266    <span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="nb">xrange</span><span class="p">(</span><span class="n">size</span><span class="p">):</span>
267        <span class="n">entry</span> <span class="o">=</span> <span class="p">[]</span>
268        <span class="k">for</span> <span class="n">j</span> <span class="ow">in</span> <span class="nb">xrange</span><span class="p">(</span><span class="n">dimension</span><span class="p">):</span>
269            <span class="n">entry</span><span class="o">.</span><span class="n">append</span><span class="p">(</span> <span class="p">((</span><span class="n">u_bound</span><span class="p">[</span><span class="n">j</span><span class="p">]</span> <span class="o">-</span> <span class="n">l_bound</span><span class="p">[</span><span class="n">j</span><span class="p">])</span> <span class="o">*</span> <span class="n">random</span><span class="p">())</span> <span class="o">+</span> <span class="n">l_bound</span><span class="p">[</span><span class="n">j</span><span class="p">]</span> <span class="p">)</span>
270        <span class="n">result</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">numpy</span><span class="o">.</span><span class="n">array</span><span class="p">(</span><span class="n">entry</span><span class="p">))</span>
271    <span class="k">return</span> <span class="n">result</span></div>
272</pre></div>
273
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