inline void merge_sort_by_key_on_gpu(KeyIterator keys_first,
KeyIterator keys_last,
ValueIterator values_first,
Compare compare,
bool stable,
command_queue &queue)
{
typedef typename std::iterator_traits<KeyIterator>::value_type key_type;
typedef typename std::iterator_traits<ValueIterator>::value_type value_type;
size_t count = iterator_range_size(keys_first, keys_last);
if(count < 2){
return;
}
size_t block_size =
block_sort(
keys_first, values_first,
compare, count,
true /* sort_by_key */, stable /* stable */,
queue
);
// for small input size only block sort is performed
if(count <= block_size) {
return;
}
const context &context = queue.get_context();
bool result_in_temporary_buffer = false;
::boost::compute::vector<key_type> temp_keys(count, context);
::boost::compute::vector<value_type> temp_values(count, context);
for(; block_size < count; block_size *= 2) {
result_in_temporary_buffer = !result_in_temporary_buffer;
if(result_in_temporary_buffer) {
merge_blocks_on_gpu(keys_first, values_first,
temp_keys.begin(), temp_values.begin(),
compare, count, block_size,
true /* sort_by_key */, queue);
} else {
merge_blocks_on_gpu(temp_keys.begin(), temp_values.begin(),
keys_first, values_first,
compare, count, block_size,
true /* sort_by_key */, queue);
}
}
if(result_in_temporary_buffer) {
copy_async(temp_keys.begin(), temp_keys.end(), keys_first, queue);
copy_async(temp_values.begin(), temp_values.end(), values_first, queue);
}
}
void bucket_sort(ForwardIterator begin,
ForwardIterator end,
ItemToRankMap rank,
SizeType range = 0)
{
#ifdef BOOST_GRAPH_PREFER_STD_LIB
std::stable_sort(begin, end, rank_comparison<ItemToRankMap>(rank));
#else
typedef std::vector
< typename boost::property_traits<ItemToRankMap>::key_type >
vector_of_values_t;
typedef std::vector< vector_of_values_t > vector_of_vectors_t;
if (!range)
{
rank_comparison<ItemToRankMap> cmp(rank);
ForwardIterator max_by_rank = std::max_element(begin, end, cmp);
if (max_by_rank == end)
return;
range = get(rank, *max_by_rank) + 1;
}
vector_of_vectors_t temp_values(range);
for(ForwardIterator itr = begin; itr != end; ++itr)
{
temp_values[get(rank, *itr)].push_back(*itr);
}
ForwardIterator orig_seq_itr = begin;
typename vector_of_vectors_t::iterator itr_end = temp_values.end();
for(typename vector_of_vectors_t::iterator itr = temp_values.begin();
itr != itr_end; ++itr
)
{
typename vector_of_values_t::iterator jtr_end = itr->end();
for(typename vector_of_values_t::iterator jtr = itr->begin();
jtr != jtr_end; ++jtr
)
{
*orig_seq_itr = *jtr;
++orig_seq_itr;
}
}
#endif
}
double SteepestDescent::do_optimize(unsigned int max_steps)
{
IMP_OBJECT_LOG;
Float last_score, new_score = 0.0;
// set up the indexes
FloatIndexes float_indexes=get_optimized_attributes();
Float current_step_size = step_size_;
// ... and space for the old values
algebra::VectorKD temp_derivs(Floats(float_indexes.size(), 0));
algebra::VectorKD temp_values(Floats(float_indexes.size(), 0));
for (unsigned int step = 0; step < max_steps; step++) {
// model.show(std::cout);
int cnt = 0;
// evaluate the last model state
last_score = get_scoring_function()->evaluate(true);
IMP_LOG(TERSE, "start score: " << last_score << std::endl);
// store the old values
for (unsigned int i = 0; i < temp_derivs.get_dimension(); i++) {
temp_derivs[i] = get_derivative(float_indexes[i]);
temp_values[i] = get_value(float_indexes[i]);
}
bool constant_score=false;
while (true) {
cnt++;
// try new values based on moving down the gradient at the current
// step size
IMP_LOG(VERBOSE, "step: "
<< temp_derivs * current_step_size << std::endl);
for (unsigned int i = 0; i < float_indexes.size(); i++) {
set_value(float_indexes[i],
temp_values[i] - temp_derivs[i]
* current_step_size);
}
// check the new model
new_score = get_scoring_function()->evaluate(false);
IMP_LOG(TERSE, "last score: " << last_score << " new score: "
<< new_score << " step size: " << current_step_size
<< std::endl);
// if the score got better, we'll take it
if (new_score < last_score) {
IMP_LOG(TERSE, "Accepting step of size "
<< current_step_size);
update_states();
if (new_score <= threshold_) {
IMP_LOG(TERSE, "Below threshold, returning." << std::endl);
return new_score;
}
current_step_size= std::min(current_step_size* 1.4,
max_step_size_);
break;
}
// if the score is the same, keep going one more time
if (std::abs(new_score- last_score) < .0000001) {
if (constant_score) {
break;
}
current_step_size *= 0.9;
constant_score = true;
} else {
constant_score=false;
current_step_size*=.7;
}
if (cnt>200) {
// stuck
for (unsigned int i = 0; i < float_indexes.size(); i++) {
set_value(float_indexes[i],
temp_values[i]);
}
IMP_LOG(TERSE, "Unable to find a good step. Returning" << std::endl);
return last_score;
}
if (current_step_size <.00000001) {
// here is as good as any place we found
update_states();
IMP_LOG(TERSE, "Unable to make progress, returning." << std::endl);
return new_score;
}
}
}
return new_score;
}