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#ifndef moses_Normalizer_h
#define moses_Normalizer_h
#include <vector>
#include "Util.h"
namespace Discriminative
{
class Normalizer
{
public:
virtual void operator()(std::vector<float> &losses) const = 0;
virtual ~Normalizer() {}
};
class SquaredLossNormalizer : public Normalizer
{
public:
virtual void operator()(std::vector<float> &losses) const {
// This is (?) a good choice for sqrt loss (default loss function in VW)
float sum = 0;
// clip to [0,1] and take 1-Z as non-normalized prob
std::vector<float>::iterator it;
for (it = losses.begin(); it != losses.end(); it++) {
if (*it <= 0.0) *it = 1.0;
else if (*it >= 1.0) *it = 0.0;
else *it = 1.0 - *it;
sum += *it;
}
if (! Moses::Equals(sum, 0)) {
// normalize
for (it = losses.begin(); it != losses.end(); it++)
*it /= sum;
} else {
// sum of non-normalized probs is 0, then take uniform probs
for (it = losses.begin(); it != losses.end(); it++)
*it = 1.0 / losses.size();
}
}
virtual ~SquaredLossNormalizer() {}
};
class LogisticLossNormalizer : public Normalizer
{
public:
virtual void operator()(std::vector<float> &losses) const {
float sum = 0;
std::vector<float>::iterator it;
for (it = losses.begin(); it != losses.end(); it++) {
*it = exp(-*it);
sum += *it;
}
for (it = losses.begin(); it != losses.end(); it++) {
*it /= sum;
}
}
virtual ~LogisticLossNormalizer() {}
};
} // namespace Discriminative
#endif // moses_Normalizer_h
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