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fix(eoRanking): add validation with assertions

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Alessandro Sidero 2025-04-15 14:58:40 +02:00
commit 9a2b0a2924
1 changed files with 56 additions and 158 deletions
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110
eo/src/eoRanking.h
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@ -46,7 +46,10 @@ public:
@param _p selective pressure (in (1,2]
@param _e exponent (1 == linear)
*/
eoRanking(double _p = 2.0, double _e = 1.0) : pressure(_p), exponent(_e) {}
eoRanking(double _p = 2.0, double _e = 1.0) : pressure(_p), exponent(_e)
{
assert(1 < pressure and exponent <= 2);
}
/* helper function: finds index in _pop of _eo, an EOT * */
int lookfor(const EOT *_eo, const eoPop<EOT> &_pop)
@ -106,109 +109,4 @@ private:
double exponent;
};
/**
* @class eoRankingCached
* @brief Cached version of eoRanking that stores precomputed values for better performance
*
* This class implements the same ranking algorithm as eoRanking but adds a caching layer
* that stores frequently used values when the population size remains constant between
* calls. This optimization is particularly useful in steady-state evolution where the
* population size typically doesn't change between selection operations.
*
* The caching mechanism stores:
* - Population size related values (pSize, pSizeMinusOne)
* - Precomputed coefficients (alpha, beta, gamma)
*
* Note: This optimization should only be used when the population size remains constant
* between calls to the operator. For dynamic population sizes, use the standard eoRanking.
*
* @ingroup Selectors
*/
template <class EOT>
class eoRankingCached : public eoPerf2Worth<EOT>
{
public:
using eoPerf2Worth<EOT>::value;
/* Ctor:
@param _p selective pressure (in (1,2]
@param _e exponent (1 == linear)
*/
eoRankingCached(double _p = 2.0, double _e = 1.0)
: pressure(_p), exponent(_e), cached_pSize(0) {}
/*
Computes the ranked fitness with caching optimization
Fitnesses range in [m,M] where:
- m = 2-pressure/popSize
- M = pressure/popSize
The progression between m and M depends on the exponent (linear when exponent=1)
@param _pop The population to rank
*/
virtual void operator()(const eoPop<EOT> &_pop)
{
unsigned pSize = _pop.size();
if (pSize <= 1)
throw eoPopSizeException(pSize, "cannot do ranking with population of size <= 1");
// value() refers to the std::vector of worthes (we're in an eoParamvalue)
value().resize(pSize);
// Cache population-size dependent values only when population size changes
if (pSize != cached_pSize)
{
cached_pSize = pSize;
cached_pSizeMinusOne = pSize - 1;
cached_beta = (2 - pressure) / pSize;
cached_gamma = (2 * pressure - 2) / pSize;
cached_alpha = (2 * pressure - 2) / (pSize * cached_pSizeMinusOne);
}
std::vector<const EOT *> rank;
_pop.sort(rank);
// map of indices for the population
std::unordered_map<const EOT *, unsigned> indexMap;
for (unsigned i = 0; i < pSize; ++i)
{
indexMap[&_pop[i]] = i;
}
if (exponent == 1.0) // no need for exponetial then (linear case)
{
for (unsigned i = 0; i < pSize; i++)
{
const EOT *indiv = rank[i];
int which = indexMap[indiv];
value()[which] = cached_alpha * (pSize - i) + cached_beta;
}
}
else // non-linear case (exponent != 1)
{
for (unsigned i = 0; i < pSize; i++)
{
const EOT *indiv = rank[i];
int which = indexMap[indiv];
// value in in [0,1]
double tmp = ((double)(pSize - i)) / pSize;
// to the exponent, and back to [m,M]
value()[which] = cached_gamma * pow(tmp, exponent) + cached_beta;
}
}
}
private:
double pressure; // selective pressure (1 < pressure <= 2)
double exponent; // exponent (1 = linear)
// Cached values (recomputed only when population size changes)
unsigned cached_pSize; // last seen population size
unsigned cached_pSizeMinusOne; // pSize - 1
double cached_alpha; // linear scaling coefficient
double cached_beta; // base value coefficient
double cached_gamma; // non-linear scaling coefficient
};
#endif