|
|
|
@ -346,27 +346,21 @@ inline LshTable<unsigned char>::LshTable(unsigned int feature_size, unsigned int |
|
|
|
|
mask_ = std::vector<size_t>((size_t)ceil((float)(feature_size * sizeof(char)) / (float)sizeof(size_t)), 0); |
|
|
|
|
|
|
|
|
|
// A bit brutal but fast to code
|
|
|
|
|
static std::vector<size_t>* indices = NULL; |
|
|
|
|
static std::vector<size_t> indices(feature_size * CHAR_BIT); |
|
|
|
|
|
|
|
|
|
//Ensure the Nth bit will be selected only once among the different LshTables
|
|
|
|
|
//to avoid having two different tables with signatures sharing many dimensions/many bits
|
|
|
|
|
if( indices == NULL ) |
|
|
|
|
if( (indices.size() == feature_size * CHAR_BIT) || (indices.size() < key_size_) ) |
|
|
|
|
{ |
|
|
|
|
indices = new std::vector<size_t>( feature_size * CHAR_BIT ); |
|
|
|
|
} |
|
|
|
|
else if( indices->size() < key_size_ ) |
|
|
|
|
{ |
|
|
|
|
indices->resize( feature_size * CHAR_BIT ); |
|
|
|
|
for (size_t i = 0; i < feature_size * CHAR_BIT; ++i) { |
|
|
|
|
(*indices)[i] = i; |
|
|
|
|
} |
|
|
|
|
std::random_shuffle(indices->begin(), indices->end()); |
|
|
|
|
indices.resize( feature_size * CHAR_BIT ); |
|
|
|
|
for (size_t i = 0; i < feature_size * CHAR_BIT; ++i) indices[i] = i; |
|
|
|
|
std::random_shuffle(indices.begin(), indices.end()); |
|
|
|
|
} |
|
|
|
|
|
|
|
|
|
// Generate a random set of order of subsignature_size_ bits
|
|
|
|
|
for (unsigned int i = 0; i < key_size_; ++i) { |
|
|
|
|
size_t index = (*indices)[0]; |
|
|
|
|
indices->erase( indices->begin() ); |
|
|
|
|
size_t index = indices[0]; |
|
|
|
|
indices.erase( indices.begin() ); |
|
|
|
|
|
|
|
|
|
// Set that bit in the mask
|
|
|
|
|
size_t divisor = CHAR_BIT * sizeof(size_t); |
|
|
|
|