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/*
Copyright (c) by respective owners including Yahoo!, Microsoft, and
individual contributors. All rights reserved. Released under a BSD (revised)
license as described in the file LICENSE.
*/
#include <float.h>
#include <sstream>
#include <queue>
#include "reductions.h"
#include "vw.h"
namespace TOPK {
typedef pair<float, v_array<char> > scored_example;
struct compare_scored_examples
{
bool operator()(scored_example const& a, scored_example const& b) const
{ return a.first > b.first; }
};
struct topk{
uint32_t B; //rec number
priority_queue<scored_example, vector<scored_example>, compare_scored_examples > pr_queue;
vw* all;
};
void print_result(int f, priority_queue<scored_example, vector<scored_example>, compare_scored_examples > &pr_queue)
{
if (f >= 0)
{
char temp[30];
std::stringstream ss;
scored_example tmp_example;
while(!pr_queue.empty())
{
tmp_example = pr_queue.top();
pr_queue.pop();
sprintf(temp, "%f", tmp_example.first);
ss << temp;
ss << ' ';
print_tag(ss, tmp_example.second);
ss << ' ';
ss << '\n';
}
ss << '\n';
ssize_t len = ss.str().size();
#ifdef _WIN32
ssize_t t = _write(f, ss.str().c_str(), (unsigned int)len);
#else
ssize_t t = write(f, ss.str().c_str(), (unsigned int)len);
#endif
if (t != len)
cerr << "write error" << endl;
}
}
void output_example(vw& all, topk& d, example& ec)
{
label_data& ld = ec.l.simple;
if (ld.label != FLT_MAX)
all.sd->weighted_labels += ld.label * ld.weight;
all.sd->weighted_examples += ld.weight;
all.sd->sum_loss += ec.loss;
all.sd->sum_loss_since_last_dump += ec.loss;
all.sd->total_features += ec.num_features;
all.sd->example_number++;
if (example_is_newline(ec))
for (int* sink = all.final_prediction_sink.begin; sink != all.final_prediction_sink.end; sink++)
TOPK::print_result(*sink, d.pr_queue);
print_update(all, ec);
}
template <bool is_learn>
void predict_or_learn(topk& d, LEARNER::base_learner& base, example& ec)
{
if (example_is_newline(ec)) return;//do not predict newline
if (is_learn)
base.learn(ec);
else
base.predict(ec);
if(d.pr_queue.size() < d.B)
d.pr_queue.push(make_pair(ec.pred.scalar, ec.tag));
else if(d.pr_queue.top().first < ec.pred.scalar)
{
d.pr_queue.pop();
d.pr_queue.push(make_pair(ec.pred.scalar, ec.tag));
}
}
void finish_example(vw& all, topk& d, example& ec)
{
TOPK::output_example(all, d, ec);
VW::finish_example(all, &ec);
}
LEARNER::base_learner* setup(vw& all)
{
new_options(all, "TOP K options")
("top", po::value<size_t>(), "top k recommendation");
if(missing_required(all)) return NULL;
topk& data = calloc_or_die<topk>();
data.B = (uint32_t)all.vm["top"].as<size_t>();
data.all = &all;
LEARNER::learner<topk>& l = init_learner(&data, setup_base(all), predict_or_learn<true>,
predict_or_learn<false>);
l.set_finish_example(finish_example);
return make_base(l);
}
}
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