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Added some safety test in roulette_wheel procedures:

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if total is zero, used to return iterator -1 - now returns uniform choice
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evomarc 2000-10-30 14:54:29 +00:00
commit 01e4aa9cdc
1 changed files with 10 additions and 0 deletions
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10
eo/src/utils/selectors.h
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@ -132,7 +132,11 @@ double sum_fitness(const eoPop<EOT>& _pop, std::pair<double, double>& _minmax)
template <class It> template <class It>
It roulette_wheel(It _begin, It _end, double total, eoRng& _gen = rng) It roulette_wheel(It _begin, It _end, double total, eoRng& _gen = rng)
{ {
float roulette = _gen.uniform(total); float roulette = _gen.uniform(total);
if (roulette == 0.0) // covers the case where total==0.0
return _min + _gen.random(_end - _min); // uniform choice
It i = _begin; It i = _begin;
@ -149,6 +153,9 @@ const EOT& roulette_wheel(const eoPop<EOT>& _pop, double total, eoRng& _gen = rn
{ {
float roulette = _gen.uniform(total); float roulette = _gen.uniform(total);
if (roulette == 0.0) // covers the case where total==0.0
return _pop[_gen.random(_pop.size())]; // uniform choice
eoPop<EOT>::const_iterator i = _pop.begin(); eoPop<EOT>::const_iterator i = _pop.begin();
while (roulette > 0.0) while (roulette > 0.0)
@ -164,6 +171,9 @@ EOT& roulette_wheel(eoPop<EOT>& _pop, double total, eoRng& _gen = rng)
{ {
float roulette = _gen.uniform(total); float roulette = _gen.uniform(total);
if (roulette == 0.0) // covers the case where total==0.0
return _pop[_gen.random(_pop.size())]; // uniform choice
eoPop<EOT>::iterator i = _pop.begin(); eoPop<EOT>::iterator i = _pop.begin();
while (roulette > 0.0) while (roulette > 0.0)