205 lines
6.4 KiB
C++
205 lines
6.4 KiB
C++
// -*- mode: c++; c-indent-level: 4; c++-member-init-indent: 8; comment-column: 35; -*-
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//-----------------------------------------------------------------------------
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// eoHowMany_h.h
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// Base class for choosing a number of guys to apply something from a popsize
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// (c) Marc Schoenauer, 2000
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// (c) Thales group, 2010 (Johann Dréo <johann.dreo@thalesgroup.com>)
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/*
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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Contact: http://eodev.sourceforge.net
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*/
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//-----------------------------------------------------------------------------
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#ifndef eoHowMany_h
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#define eoHowMany_h
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#include <sstream>
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#include <utils/eoLogger.h>
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/** A helper class, to determine a number of individuals from another one
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* Typically, is used in selection / replacement procedures, e.g.
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* the number of offspring from the number of parents, or
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* the number of survivors for an eoReduce functor, ...
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*
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* Such construct is very useful because in some cases you might not know the
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* population size that will enter the replacement. For instance, you
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* cannot simply have a pre-computed (double) rate of 1/popSize
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* if you want to select or kill just 1 guy. Using an eoHowMany
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* allows one to modify the population size without touching anything else.
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*
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* There are 4 possible way to compute the return value from the argument:
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* - an absolute POSITIVE integer --> return it (regardless of popsize)
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* - a POSITIVE rate --> return rate*popSize
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* - an absolute NEGATIVE integer --> return popsize-rate (if positive)
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* - a NEGATIVE rate in [-1,0] --> store and use 1-|rate| (positive)
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* Note that a negative rate should be have been necessary because a rate is
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* relative, but it is there for consistency reasons - and because it
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* is needed in <a href="classeo_g3_replacement_h-source.html">eoG3Replacement</a>
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*
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* It has 2 private members, a double and an integer to cover all cases
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*
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* Example use: in <a href="class_eogeneralbreeder.html">eoGeneralBreeder.h</a>
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* Example reading from parser: in
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* <a href="make_algo_scalar_h-source.html">do/make_algo_scalar.h line 141</a>
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* MS 10/04/2002:
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* Added the possibility to have a negative number -
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* when treated as a number: returns then (size - count)
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* Should not modify anything when a positive number is passed in the ctor
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*
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* MS 20/06/2002:
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* Added the negative rate and the operator-() (for
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* eoG3Repalcement)
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*
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* It is an eoPersistent because we need to be able to use eoParamValue<eoHowMany>
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*
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* @ingroup Core
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*/
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class eoHowMany : public eoPersistent
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{
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public:
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/** Original Ctor from direct rate + bool
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@param rate the rate, OR the integer to store, depending on 2nd arg.
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@param _interpret_as_rate to tell whether the rate actually is a rate
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*/
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eoHowMany(double _rate = 0.0, bool _interpret_as_rate = true):
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rate(_rate), count(0)
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{
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if (_interpret_as_rate)
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{
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if (_rate<0)
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{
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rate = 1.0+_rate;
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if (rate < 0) // was < -1
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throw std::logic_error("rate<-1 in eoHowMany!");
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}
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}
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else
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{
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rate = 0.0; // just in case, but shoud be unused
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count = int(_rate); // negative values are allowed here
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if (count != _rate)
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eo::log << eo::warnings << "Number was rounded in eoHowMany";
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}
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}
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/** Ctor from an int - both from int and unsigned int are needed
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* to avoid ambiguity with the Ctor from a double */
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eoHowMany(int _count) : rate(0.0), count(_count) {}
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/** Ctor from an unsigned int - both from int and unsigned int are needed
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* to avoid ambiguity with the Ctor from a double */
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eoHowMany(unsigned int _count) : rate(0.0), count(_count) {}
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/// Virtual dtor. They are needed in virtual class hierarchies.
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virtual ~eoHowMany() {}
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/** Does what it was designed for
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* - count==0 : return rate*_size
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* - else
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* - count>0 : return count (regardless of _size)
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* - count<0 : return _size-|count|
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*/
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unsigned int operator()(unsigned int _size)
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{
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if (count == 0)
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{
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unsigned int res = static_cast<unsigned int>( std::ceil( rate * _size ) );
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if( res == 0 ) {
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eo::log << eo::warnings << "Call to a eoHowMany instance returns 0 (rate=" << rate << ", size=" << _size << ")" << std::endl;
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}
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return res;
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}
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if (count < 0)
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{
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unsigned int combloc = -count;
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if (_size<combloc)
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throw std::runtime_error("Negative result in eoHowMany");
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return _size-combloc;
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}
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return unsigned(count);
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}
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virtual void printOn(std::ostream& _os) const
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{
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if (count == 0)
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_os << 100*rate << "% ";
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else
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_os << count << " ";
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return;
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}
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virtual void readFrom(std::istream& _is)
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{
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std::string value;
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_is >> value;
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readFrom(value);
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return;
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}
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void readFrom(std::string _value)
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{
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// check for %
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bool interpret_as_rate = false; // == no %
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size_t pos = _value.find('%');
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if (pos < _value.size()) // found a %
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{
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interpret_as_rate = true;
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_value.resize(pos); // get rid of %
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}
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std::istringstream is(_value);
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is >> rate;
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// now store
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if (interpret_as_rate)
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{
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count = 0;
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rate /= 100.0;
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}
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else
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count = int(rate); // and rate will not be used
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// minimal check
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if ( rate < 0.0 )
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throw std::runtime_error("Negative rate read in eoHowMany::readFrom");
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}
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/** The unary - operator: reverses the computation */
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eoHowMany operator-()
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{
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if (!count) // only rate is used
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rate = 1.0-rate;
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else
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count = -count;
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return (*this);
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}
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private :
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double rate;
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int count;
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};
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#endif
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