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<div class="subTitle">jcgp.backend.modules.problem</div>
<h2 title="Class Problem" class="title">Class Problem</h2>
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<ul class="inheritance">
<li>java.lang.Object</li>
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<li><a href="../../../../jcgp/backend/modules/Module.html" title="class in jcgp.backend.modules">jcgp.backend.modules.Module</a></li>
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<li>jcgp.backend.modules.problem.Problem</li>
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<dt>Direct Known Subclasses:</dt>
<dd><a href="../../../../jcgp/backend/modules/problem/TestCaseProblem.html" title="class in jcgp.backend.modules.problem">TestCaseProblem</a></dd>
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<pre>public abstract class <span class="typeNameLabel">Problem</span>
extends <a href="../../../../jcgp/backend/modules/Module.html" title="class in jcgp.backend.modules">Module</a></pre>
<div class="block">Defines the general behaviour of a CGP problem. The primary function of <code>Problem</code>
is to evaluate a population and assign a fitness value to each chromosome.
<br>
Problems are free to define whether better fitness means a higher or lower fitness value.
In some problem types, it is more convenient to treat fitness 0 as the best possible value.
This can be done by changing the fitness orientation to <code>BestFitness.HIGH</code> or <code>BestFitness.LOW</code> as appropriate.
Fitness orientation is set to high by default.
<br><br>
When extending this class, the constructor should call a few methods in order to
properly construct the problem type: <code>setFunctionSet()</code>, <code>setFileExtension()</code> and <code>setFitnessOrientation()</code>,
with the respective arguments. As with all subclasses of <code>Module</code>, <code>setName()</code> and
<code>registerParameters()</code> should be used where appropriate as well.
<br><br>
It is advisable to use <code>Resources.reportln()</code> and <code>Resources.report()</code>
to print any relevant information. Note that reportln() and report() are affected
by the report interval base parameter. Use <code>Resources.println()</code> and
<code>Resources.print()</code> to print information regardless of the current generation.
See <a href="../../../../jcgp/backend/resources/Resources.html" title="class in jcgp.backend.resources"><code>Resources</code></a> for more information.</div>
<dl>
<dt><span class="simpleTagLabel">Author:</span></dt>
<dd>Eduardo Pedroni</dd>
<dt><span class="seeLabel">See Also:</span></dt>
<dd><a href="../../../../jcgp/backend/modules/Module.html" title="class in jcgp.backend.modules"><code>Module</code></a></dd>
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<th class="colOne" scope="col">Constructor and Description</th>
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<td class="colOne"><code><span class="memberNameLink"><a href="../../../../jcgp/backend/modules/problem/Problem.html#Problem-jcgp.backend.resources.Resources-">Problem</a></span>(<a href="../../../../jcgp/backend/resources/Resources.html" title="class in jcgp.backend.resources">Resources</a> resources)</code>
<div class="block">Initialises the two problem-wide parameters, maxFitness and bestFitness.</div>
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<td class="colFirst"><code>abstract void</code></td>
<td class="colLast"><code><span class="memberNameLink"><a href="../../../../jcgp/backend/modules/problem/Problem.html#evaluate-jcgp.backend.population.Population-jcgp.backend.resources.Resources-">evaluate</a></span>(<a href="../../../../jcgp/backend/population/Population.html" title="class in jcgp.backend.population">Population</a> population,
<a href="../../../../jcgp/backend/resources/Resources.html" title="class in jcgp.backend.resources">Resources</a> resources)</code>
<div class="block">The most important method of the problem type.</div>
</td>
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<tr id="i1" class="rowColor">
<td class="colFirst"><code>double</code></td>
<td class="colLast"><code><span class="memberNameLink"><a href="../../../../jcgp/backend/modules/problem/Problem.html#getBestFitness--">getBestFitness</a></span>()</code> </td>
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<tr id="i2" class="altColor">
<td class="colFirst"><code>java.lang.String</code></td>
<td class="colLast"><code><span class="memberNameLink"><a href="../../../../jcgp/backend/modules/problem/Problem.html#getFileExtension--">getFileExtension</a></span>()</code> </td>
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<tr id="i3" class="rowColor">
<td class="colFirst"><code><a href="../../../../jcgp/backend/modules/problem/BestFitness.html" title="enum in jcgp.backend.modules.problem">BestFitness</a></code></td>
<td class="colLast"><code><span class="memberNameLink"><a href="../../../../jcgp/backend/modules/problem/Problem.html#getFitnessOrientation--">getFitnessOrientation</a></span>()</code> </td>
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<tr id="i4" class="altColor">
<td class="colFirst"><code><a href="../../../../jcgp/backend/function/FunctionSet.html" title="class in jcgp.backend.function">FunctionSet</a></code></td>
<td class="colLast"><code><span class="memberNameLink"><a href="../../../../jcgp/backend/modules/problem/Problem.html#getFunctionSet--">getFunctionSet</a></span>()</code> </td>
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<tr id="i5" class="rowColor">
<td class="colFirst"><code>abstract int</code></td>
<td class="colLast"><code><span class="memberNameLink"><a href="../../../../jcgp/backend/modules/problem/Problem.html#hasImprovement-jcgp.backend.population.Population-">hasImprovement</a></span>(<a href="../../../../jcgp/backend/population/Population.html" title="class in jcgp.backend.population">Population</a> population)</code>
<div class="block">Used to assert whether a given population has a chromosome that is an improvement over
the current best chromosome.</div>
</td>
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<tr id="i6" class="altColor">
<td class="colFirst"><code>abstract void</code></td>
<td class="colLast"><code><span class="memberNameLink"><a href="../../../../jcgp/backend/modules/problem/Problem.html#parseProblemData-java.io.File-jcgp.backend.resources.ModifiableResources-">parseProblemData</a></span>(java.io.File file,
<a href="../../../../jcgp/backend/resources/ModifiableResources.html" title="class in jcgp.backend.resources">ModifiableResources</a> resources)</code>
<div class="block">Parses the specified file and uses the parsed data to
set up the problem type instance appropriately.</div>
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<tr id="i7" class="rowColor">
<td class="colFirst"><code>abstract int</code></td>
<td class="colLast"><code><span class="memberNameLink"><a href="../../../../jcgp/backend/modules/problem/Problem.html#perfectSolutionFound-jcgp.backend.population.Population-">perfectSolutionFound</a></span>(<a href="../../../../jcgp/backend/population/Population.html" title="class in jcgp.backend.population">Population</a> population)</code>
<div class="block">Used to assert whether a given population contains a perfect solution
to the problem.</div>
</td>
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<tr id="i8" class="altColor">
<td class="colFirst"><code>void</code></td>
<td class="colLast"><code><span class="memberNameLink"><a href="../../../../jcgp/backend/modules/problem/Problem.html#reset--">reset</a></span>()</code>
<div class="block">Resets the bestFitness parameter.</div>
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<h3>Methods inherited from class jcgp.backend.modules.<a href="../../../../jcgp/backend/modules/Module.html" title="class in jcgp.backend.modules">Module</a></h3>
<code><a href="../../../../jcgp/backend/modules/Module.html#getLocalParameters--">getLocalParameters</a>, <a href="../../../../jcgp/backend/modules/Module.html#toString--">toString</a></code></li>
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<code>equals, getClass, hashCode, notify, notifyAll, wait, wait, wait</code></li>
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<h4>Problem</h4>
<pre>public Problem(<a href="../../../../jcgp/backend/resources/Resources.html" title="class in jcgp.backend.resources">Resources</a> resources)</pre>
<div class="block">Initialises the two problem-wide parameters, maxFitness and bestFitness.</div>
<dl>
<dt><span class="paramLabel">Parameters:</span></dt>
<dd><code>resources</code> - a reference to the experiment's resources.</dd>
</dl>
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<h4>evaluate</h4>
<pre>public abstract void evaluate(<a href="../../../../jcgp/backend/population/Population.html" title="class in jcgp.backend.population">Population</a> population,
<a href="../../../../jcgp/backend/resources/Resources.html" title="class in jcgp.backend.resources">Resources</a> resources)</pre>
<div class="block">The most important method of the problem type. This is called once
per generation, when the new population has been generated.
<br><br>
The basic functionality of this method is to loop through all chromosomes
in the population and decode them according to the problem type. The
fitness of each chromosome is then calculated using the problem data
or otherwise (subjective problem types such as art generation might
leave fitness evaluations up to the user) and assigned to the appropriate
chromosome.
<br><br>
In addition, realisations of this method should update the value of
bestFitness as appropriate, since the value of this parameter is displayed
if a GUI is in use.</div>
<dl>
<dt><span class="paramLabel">Parameters:</span></dt>
<dd><code>population</code> - the population to be evaluated.</dd>
<dd><code>resources</code> - parameters and utilities for optional reference.</dd>
</dl>
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<h4>perfectSolutionFound</h4>
<pre>public abstract int perfectSolutionFound(<a href="../../../../jcgp/backend/population/Population.html" title="class in jcgp.backend.population">Population</a> population)</pre>
<div class="block">Used to assert whether a given population contains a perfect solution
to the problem. It is up to the problem to define what qualifies
a perfect solution, as some problems (subject ones such as music and
art evolution, for example) might not have perfect solutions at all.</div>
<dl>
<dt><span class="paramLabel">Parameters:</span></dt>
<dd><code>population</code> - the population to search through for a perfect chromosome.</dd>
<dt><span class="returnLabel">Returns:</span></dt>
<dd>the perfect solution index, if one exits, -1 if no perfect solution was found.</dd>
</dl>
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<h4>hasImprovement</h4>
<pre>public abstract int hasImprovement(<a href="../../../../jcgp/backend/population/Population.html" title="class in jcgp.backend.population">Population</a> population)</pre>
<div class="block">Used to assert whether a given population has a chromosome that is an improvement over
the current best chromosome. A typical implementation of this method
will simply compare chromosome fitness values, though the problem type
is free to implement this in any way.</div>
<dl>
<dt><span class="paramLabel">Parameters:</span></dt>
<dd><code>population</code> - the population potentially containing a fitter chromosome.</dd>
<dt><span class="returnLabel">Returns:</span></dt>
<dd>the index of the first chromosome in the population that is an improvement, -1 if none is found.</dd>
</dl>
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<h4>parseProblemData</h4>
<pre>public abstract void parseProblemData(java.io.File file,
<a href="../../../../jcgp/backend/resources/ModifiableResources.html" title="class in jcgp.backend.resources">ModifiableResources</a> resources)</pre>
<div class="block">Parses the specified file and uses the parsed data to
set up the problem type instance appropriately. Any necessary
resource changes can be performed using the provided <code>ModifiableResources</code>
instance.
<br><br>
In addition, realisations of this method should update the value of
maxFitness where appropriate, as this may be displayed to the user
if a GUI is in use.</div>
<dl>
<dt><span class="paramLabel">Parameters:</span></dt>
<dd><code>file</code> - the data file to parse.</dd>
<dd><code>resources</code> - a modifiable reference to the experiment's resources.</dd>
</dl>
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<h4>getFunctionSet</h4>
<pre>public <a href="../../../../jcgp/backend/function/FunctionSet.html" title="class in jcgp.backend.function">FunctionSet</a> getFunctionSet()</pre>
<dl>
<dt><span class="returnLabel">Returns:</span></dt>
<dd>the FunctionSet object used by this problem type.</dd>
</dl>
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<h4>getFileExtension</h4>
<pre>public java.lang.String getFileExtension()</pre>
<dl>
<dt><span class="returnLabel">Returns:</span></dt>
<dd>the file extension accepted by this problem type for problem data files.</dd>
</dl>
</li>
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<h4>getFitnessOrientation</h4>
<pre>public <a href="../../../../jcgp/backend/modules/problem/BestFitness.html" title="enum in jcgp.backend.modules.problem">BestFitness</a> getFitnessOrientation()</pre>
<dl>
<dt><span class="returnLabel">Returns:</span></dt>
<dd>the fitness orientation of this particular problem.</dd>
</dl>
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<h4>getBestFitness</h4>
<pre>public double getBestFitness()</pre>
<dl>
<dt><span class="returnLabel">Returns:</span></dt>
<dd>the current best fitness, in other words, the fitness
value of the fittest chromosome in the current generation.</dd>
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<h4>reset</h4>
<pre>public void reset()</pre>
<div class="block">Resets the bestFitness parameter.</div>
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