multiclass.cc

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#include <cstring>
#include <climits>
#include "global_data.h"
#include "vw.h"
#include "vw_exception.h"

namespace MULTICLASS
{
char* bufread_label(label_t* ld, char* c)
{
  memcpy(&ld->label, c, sizeof(ld->label));
  c += sizeof(ld->label);
  memcpy(&ld->weight, c, sizeof(ld->weight));
  c += sizeof(ld->weight);
  return c;
}

size_t read_cached_label(shared_data*, void* v, io_buf& cache)
{
  label_t* ld = (label_t*)v;
  char* c;
  size_t total = sizeof(ld->label) + sizeof(ld->weight);
  if (cache.buf_read(c, total) < total)
    return 0;
  bufread_label(ld, c);

  return total;
}

float weight(void* v)
{
  label_t* ld = (label_t*)v;
  return (ld->weight > 0) ? ld->weight : 0.f;
}

char* bufcache_label(label_t* ld, char* c)
{
  memcpy(c, &ld->label, sizeof(ld->label));
  c += sizeof(ld->label);
  memcpy(c, &ld->weight, sizeof(ld->weight));
  c += sizeof(ld->weight);
  return c;
}

void cache_label(void* v, io_buf& cache)
{
  char* c;
  label_t* ld = (label_t*)v;
  cache.buf_write(c, sizeof(ld->label) + sizeof(ld->weight));
  bufcache_label(ld, c);
}

void default_label(void* v)
{
  label_t* ld = (label_t*)v;
  ld->label = (uint32_t)-1;
  ld->weight = 1.;
}

bool test_label(void* v)
{
  label_t* ld = (label_t*)v;
  return ld->label == (uint32_t)-1;
}

void delete_label(void*) {}

void parse_label(parser*, shared_data* sd, void* v, v_array<substring>& words)
{
  label_t* ld = (label_t*)v;

  switch (words.size())
  {
    case 0:
      break;
    case 1:
      ld->label = sd->ldict ? (uint32_t)sd->ldict->get(words[0]) : int_of_substring(words[0]);
      ld->weight = 1.0;
      break;
    case 2:
      ld->label = sd->ldict ? (uint32_t)sd->ldict->get(words[0]) : int_of_substring(words[0]);
      ld->weight = float_of_substring(words[1]);
      break;
    default:
      std::cerr << "malformed example!\n";
      std::cerr << "words.size() = " << words.size() << std::endl;
  }
  if (ld->label == 0)
    THROW("label 0 is not allowed for multiclass.  Valid labels are {1,k}"
        << (sd->ldict ? "\nthis likely happened because you specified an invalid label with named labels" : ""));
}

label_parser mc_label = {default_label, parse_label, cache_label, read_cached_label, delete_label, weight, nullptr,
    test_label, sizeof(label_t)};

void print_label_pred(vw& all, example& ec, uint32_t prediction)
{
  substring ss_label = all.sd->ldict->get(ec.l.multi.label);
  substring ss_pred = all.sd->ldict->get(prediction);
  all.sd->print_update(all.holdout_set_off, all.current_pass,
      !ss_label.begin ? "unknown" : std::string(ss_label.begin, ss_label.end - ss_label.begin),
      !ss_pred.begin ? "unknown" : std::string(ss_pred.begin, ss_pred.end - ss_pred.begin), ec.num_features,
      all.progress_add, all.progress_arg);
}

void print_probability(vw& all, example& ec, uint32_t prediction)
{
  std::stringstream pred_ss;
  pred_ss << prediction << "(" << std::setw(2) << std::setprecision(0) << std::fixed
          << 100 * ec.pred.scalars[prediction - 1] << "%)";

  std::stringstream label_ss;
  label_ss << ec.l.multi.label;

  all.sd->print_update(all.holdout_set_off, all.current_pass, label_ss.str(), pred_ss.str(), ec.num_features,
      all.progress_add, all.progress_arg);
}

void print_score(vw& all, example& ec, uint32_t prediction)
{
  std::stringstream pred_ss;
  pred_ss << prediction;

  std::stringstream label_ss;
  label_ss << ec.l.multi.label;

  all.sd->print_update(all.holdout_set_off, all.current_pass, label_ss.str(), pred_ss.str(), ec.num_features,
      all.progress_add, all.progress_arg);
}

void direct_print_update(vw& all, example& ec, uint32_t prediction)
{
  all.sd->print_update(all.holdout_set_off, all.current_pass, ec.l.multi.label, prediction, ec.num_features,
      all.progress_add, all.progress_arg);
}

template <void (*T)(vw&, example&, uint32_t)>
void print_update(vw& all, example& ec, uint32_t prediction)
{
  if (all.sd->weighted_examples() >= all.sd->dump_interval && !all.quiet && !all.bfgs)
  {
    if (!all.sd->ldict)
      T(all, ec, prediction);
    else
      print_label_pred(all, ec, ec.pred.multiclass);
  }
}

void print_update_with_probability(vw& all, example& ec, uint32_t pred)
{
  print_update<print_probability>(all, ec, pred);
}
void print_update_with_score(vw& all, example& ec, uint32_t pred) { print_update<print_score>(all, ec, pred); }

void finish_example(vw& all, example& ec, bool update_loss)
{
  float loss = 0;
  if (ec.l.multi.label != (uint32_t)ec.pred.multiclass && ec.l.multi.label != (uint32_t)-1)
    loss = ec.weight;

  all.sd->update(ec.test_only, update_loss && (ec.l.multi.label != (uint32_t)-1), loss, ec.weight, ec.num_features);

  for (int sink : all.final_prediction_sink)
    if (!all.sd->ldict)
      all.print(sink, (float)ec.pred.multiclass, 0, ec.tag);
    else
    {
      substring ss_pred = all.sd->ldict->get(ec.pred.multiclass);
      all.print_text(sink, std::string(ss_pred.begin, ss_pred.end - ss_pred.begin), ec.tag);
    }

  MULTICLASS::print_update<direct_print_update>(all, ec, ec.pred.multiclass);
  VW::finish_example(all, ec);
}
}  // namespace MULTICLASS