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lrq.cc
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lrq.cc
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#include <string.h>
#include <float.h>
#include "reductions.h"
#include "rand48.h"
#include "vw_exception.h"
#include "parse_args.h" // for spoof_hex_encoded_namespaces
using namespace LEARNER;
using namespace std;
struct LRQstate
{ vw* all; // feature creation, audit, hash_inv
bool lrindices[256];
size_t orig_size[256];
std::set<std::string> lrpairs;
bool dropout;
uint64_t seed;
uint64_t initial_seed;
};
bool valid_int (const char* s)
{ char* endptr;
int v = strtoul (s, &endptr, 0);
(void) v;
return (*s != '\0' && *endptr == '\0');
}
inline bool
cheesyrbit (uint64_t& seed)
{ return merand48 (seed) > 0.5;
}
inline float
cheesyrand (uint64_t x)
{ uint64_t seed = x;
return merand48 (seed);
}
inline bool
example_is_test (example& ec)
{ return ec.l.simple.label == FLT_MAX;
}
void
reset_seed (LRQstate& lrq)
{ if (lrq.all->bfgs)
lrq.seed = lrq.initial_seed;
}
template <bool is_learn>
void predict_or_learn(LRQstate& lrq, base_learner& base, example& ec)
{ vw& all = *lrq.all;
// Remember original features
memset (lrq.orig_size, 0, sizeof (lrq.orig_size));
for (namespace_index i : ec.indices)
{ if (lrq.lrindices[i])
lrq.orig_size[i] = ec.feature_space[i].size ();
}
size_t which = ec.example_counter;
float first_prediction = 0;
float first_loss = 0;
float first_uncertainty = 0;
unsigned int maxiter = (is_learn && ! example_is_test (ec)) ? 2 : 1;
bool do_dropout = lrq.dropout && is_learn && ! example_is_test (ec);
float scale = (! lrq.dropout || do_dropout) ? 1.f : 0.5f;
for (unsigned int iter = 0; iter < maxiter; ++iter, ++which)
{ // Add left LRQ features, holding right LRQ features fixed
// and vice versa
// TODO: what happens with --lrq ab2 --lrq ac2
// i.e. namespace occurs multiple times (?)
for (string const& i : lrq.lrpairs)
{ unsigned char left = i[which%2];
unsigned char right = i[(which+1)%2];
unsigned int k = atoi (i.c_str () + 2);
features& left_fs = ec.feature_space[left];
for (unsigned int lfn = 0; lfn < lrq.orig_size[left]; ++lfn)
{
float lfx = left_fs.values[lfn];
uint64_t lindex = left_fs.indicies[lfn] + ec.ft_offset;
weight_parameters& w = all.weights;
for (unsigned int n = 1; n <= k; ++n)
{ if (! do_dropout || cheesyrbit (lrq.seed))
{ uint64_t lwindex = (uint64_t)(lindex + (n << all.weights.stride_shift()));
weight_parameters::iterator lw = w.change_begin() + (lwindex & w.mask());
// perturb away from saddle point at (0, 0)
if (is_learn && ! example_is_test (ec) && *lw == 0)
*lw = cheesyrand (lwindex); //not sure if lw needs a weight mask?
features& right_fs = ec.feature_space[right];
for (unsigned int rfn = 0;
rfn < lrq.orig_size[right];
++rfn)
{ // NB: ec.ft_offset added by base learner
float rfx = right_fs.values[rfn];
uint64_t rindex = right_fs.indicies[rfn];
uint64_t rwindex = (uint64_t)(rindex + (n << all.weights.stride_shift()));
right_fs.push_back(scale **lw * lfx * rfx, rwindex);
if (all.audit || all.hash_inv)
{ std::stringstream new_feature_buffer;
new_feature_buffer << right << '^'
<< right_fs.space_names[rfn].get()->second << '^'
<< n;
#ifdef _WIN32
char* new_space = _strdup("lrq");
char* new_feature = _strdup(new_feature_buffer.str().c_str());
#else
char* new_space = strdup("lrq");
char* new_feature = strdup(new_feature_buffer.str().c_str());
#endif
right_fs.space_names.push_back(audit_strings_ptr(new audit_strings(new_space,new_feature)));
}
}
}
}
}
}
if (is_learn)
base.learn(ec);
else
base.predict(ec);
// Restore example
if (iter == 0)
{ first_prediction = ec.pred.scalar;
first_loss = ec.loss;
first_uncertainty = ec.confidence;
}
else
{ ec.pred.scalar = first_prediction;
ec.loss = first_loss;
ec.confidence = first_uncertainty;
}
for (string const& i : lrq.lrpairs)
{ unsigned char right = i[(which+1)%2];
ec.feature_space[right].truncate_to(lrq.orig_size[right]);
}
}
}
void finish(LRQstate& lrq) { lrq.lrpairs.~set<string>(); }
base_learner* lrq_setup(vw& all)
{ //parse and set arguments
if (missing_option<vector<string>>(all, "lrq", "use low rank quadratic features"))
return nullptr;
new_options(all, "Lrq options")
("lrqdropout", "use dropout training for low rank quadratic features");
add_options(all);
if(!all.vm.count("lrq"))
return nullptr;
LRQstate& lrq = calloc_or_throw<LRQstate>();
uint32_t maxk = 0;
lrq.all = &all;
vector<string> arg = all.vm["lrq"].as<vector<string> > ();
for (size_t i = 0; i < arg.size(); i++) arg[i] = spoof_hex_encoded_namespaces( arg[i] );
new(&lrq.lrpairs) std::set<std::string> (arg.begin(), arg.end());
lrq.initial_seed = lrq.seed = all.random_seed | 8675309;
if (all.vm.count("lrqdropout"))
{ lrq.dropout = true;
*all.file_options << " --lrqdropout ";
}
else
lrq.dropout = false;
for (auto& i : lrq.lrpairs)
*all.file_options << " --lrq " << i;
if (! all.quiet)
{ cerr << "creating low rank quadratic features for pairs: ";
if (lrq.dropout)
cerr << "(using dropout) ";
}
for (string const& i : lrq.lrpairs)
{ if(!all.quiet)
{ if (( i.length() < 3 ) || ! valid_int (i.c_str () + 2))
{ free(&lrq);
THROW("error, low-rank quadratic features must involve two sets and a rank.");
}
cerr << i << " ";
}
// TODO: colon-syntax
unsigned int k = atoi (i.c_str () + 2);
lrq.lrindices[(int) i[0]] = 1;
lrq.lrindices[(int) i[1]] = 1;
maxk = max (maxk, k);
}
if(!all.quiet)
cerr<<endl;
all.wpp = all.wpp * (uint64_t)(1 + maxk);
learner<LRQstate>& l = init_learner(&lrq, setup_base(all), predict_or_learn<true>,
predict_or_learn<false>, 1 + maxk);
l.set_end_pass(reset_seed);
l.set_finish(finish);
// TODO: leaks memory ?
return make_base(l);
}