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Commit 29964d28 authored by Davis King's avatar Davis King
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improved example a little

parent 02b63287
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Showing with 142 additions and 69 deletions
examples/sequence_labeler_ex.cpp
View file @ 29964d28
......@@ -67,8 +67,127 @@ public:
}
};
void serialize(const feature_extractor&, std::ostream&) {}
void deserialize(feature_extractor&, std::istream&) {}
// ----------------------------------------------------------------------------------------
void make_dataset (
const matrix<double>& emission_probabilities,
const matrix<double>& transition_probabilities,
std::vector<std::vector<unsigned long> >& samples,
std::vector<std::vector<unsigned long> >& labels,
unsigned long dataset_size
);
/*!
requires
- transition_probabilities.nr() == transition_probabilities.nc()
- transition_probabilities.nr() == emission_probabilities.nr()
- The rows of transition_probabilities and emission_probabilities must sum to 1.
(i.e. sum_cols(transition_probabilities) and sum_cols(emission_probabilities)
must evaluate to vectors of all 1s.)
ensures
- This function randomly samples a bunch of sequences from the HMM defined by
transition_probabilities and emission_probabilities.
- The HMM is defined by:
- P(next_label |previous_label) == transition_probabilities(previous_label, next_label)
- P(next_sample|next_label) == emission_probabilities (next_label, next_sample)
- #samples.size() == labels.size() == dataset_size
- for all valid i:
- #labels[i] is a randomly sampled sequence of hidden states from the
given HMM. #samples[i] is its corresponding randomly sampled sequence
of observed states.
!*/
// ----------------------------------------------------------------------------------------
int main()
{
// set this up so emission_probabilities(L,X) == The probability of a state with label L
// emitting an X.
matrix<double> emission_probabilities(num_label_states,num_sample_states);
emission_probabilities = 0.5, 0.5, 0.0,
0.0, 0.5, 0.5,
0.5, 0.0, 0.5;
matrix<double> transition_probabilities(num_label_states, num_label_states);
transition_probabilities = 0.05, 0.90, 0.05,
0.05, 0.05, 0.90,
0.90, 0.05, 0.05;
std::vector<std::vector<unsigned long> > samples;
std::vector<std::vector<unsigned long> > labels;
make_dataset(emission_probabilities, transition_probabilities,
samples, labels, 1000);
cout << "samples.size(): "<< samples.size() << endl;
// print out some of the randomly sampled sequences
for (int i = 0; i < 10; ++i)
{
cout << "hidden states: " << trans(vector_to_matrix(labels[i]));
cout << "observed states: " << trans(vector_to_matrix(samples[i]));
cout << "******************************" << endl;
}
structural_sequence_labeling_trainer<feature_extractor> trainer;
trainer.set_c(4);
trainer.set_num_threads(4);
matrix<double> confusion_matrix;
// Learn to do sequence labeling from the dataset
sequence_labeler<feature_extractor> labeler = trainer.train(samples, labels);
confusion_matrix = test_sequence_labeler(labeler, samples, labels);
cout << "trained sequence labeler: " << endl;
cout << confusion_matrix;
cout << "label accuracy: "<< sum(diag(confusion_matrix))/sum(confusion_matrix) << endl;
// We can also do cross-validation
confusion_matrix = cross_validate_sequence_labeler(trainer, samples, labels, 4);
cout << "\ncross-validation: " << endl;
cout << confusion_matrix;
cout << "label accuracy: "<< sum(diag(confusion_matrix))/sum(confusion_matrix) << endl;
matrix<double,0,1> true_hmm_model_weights = log(join_cols(reshape_to_column_vector(transition_probabilities),
reshape_to_column_vector(emission_probabilities)));
sequence_labeler<feature_extractor> labeler_true(feature_extractor(), true_hmm_model_weights);
confusion_matrix = test_sequence_labeler(labeler_true, samples, labels);
cout << "\nTrue HMM model: " << endl;
cout << confusion_matrix;
cout << "label accuracy: "<< sum(diag(confusion_matrix))/sum(confusion_matrix) << endl;
// Finally, the labeler can be serialized to disk just like most dlib objects.
ofstream fout("labeler.dat", ios::binary);
serialize(labeler, fout);
fout.close();
// recall from disk
ifstream fin("labeler.dat", ios::binary);
deserialize(labeler, fin);
}
// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------
// Code for creating a bunch of random samples from our HMM.
// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------
void sample_hmm (
dlib::rand& rnd,
......@@ -78,7 +197,26 @@ void sample_hmm (
unsigned long& next_label,
unsigned long& next_sample
)
/*!
requires
- previous_label < transition_probabilities.nr()
- transition_probabilities.nr() == transition_probabilities.nc()
- transition_probabilities.nr() == emission_probabilities.nr()
- The rows of transition_probabilities and emission_probabilities must sum to 1.
(i.e. sum_cols(transition_probabilities) and sum_cols(emission_probabilities)
must evaluate to vectors of all 1s.)
ensures
- This function randomly samples the HMM defined by transition_probabilities
and emission_probabilities assuming that the previous hidden state
was previous_label.
- The HMM is defined by:
- P(next_label |previous_label) == transition_probabilities(previous_label, next_label)
- P(next_sample|next_label) == emission_probabilities (next_label, next_sample)
- #next_label == the sampled value of the hidden state
- #next_sample == the sampled value of the observed state
!*/
{
// sample next_label
double p = rnd.get_random_double();
for (long c = 0; p >= 0 && c < transition_probabilities.nc(); ++c)
{
......@@ -86,7 +224,7 @@ void sample_hmm (
p -= transition_probabilities(previous_label, c);
}
// now sample next_sample
p = rnd.get_random_double();
for (long c = 0; p >= 0 && c < emission_probabilities.nc(); ++c)
{
......@@ -104,10 +242,6 @@ void make_dataset (
std::vector<std::vector<unsigned long> >& labels,
unsigned long dataset_size
)
/*!
2 kinds of label
3 kinds of input state
!*/
{
samples.clear();
labels.clear();
......@@ -117,9 +251,9 @@ void make_dataset (
// now randomly sample some labeled sequences from our Hidden Markov Model
for (unsigned long iter = 0; iter < dataset_size; ++iter)
{
const unsigned long size = rnd.get_random_32bit_number()%20+3;
std::vector<unsigned long> sample(size);
std::vector<unsigned long> label(size);
const unsigned long sequence_size = rnd.get_random_32bit_number()%20+3;
std::vector<unsigned long> sample(sequence_size);
std::vector<unsigned long> label(sequence_size);
unsigned long previous_label = rnd.get_random_32bit_number()%num_label_states;
for (unsigned long i = 0; i < sample.size(); ++i)
......@@ -141,64 +275,3 @@ void make_dataset (
// ----------------------------------------------------------------------------------------
int main()
{
std::vector<std::vector<unsigned long> > samples;
std::vector<std::vector<unsigned long> > labels;
// set this up so emission_probabilities(L,X) == The probability of a state with label L
// emitting an X.
matrix<double> emission_probabilities(num_label_states,num_sample_states);
emission_probabilities = 0.5, 0.5, 0.0,
0.0, 0.5, 0.5,
0.5, 0.0, 0.5;
matrix<double> transition_probabilities(num_label_states, num_label_states);
transition_probabilities = 0.05, 0.90, 0.05,
0.05, 0.05, 0.90,
0.90, 0.05, 0.05;
make_dataset(emission_probabilities, transition_probabilities,
samples, labels, 1000);
cout << "samples.size(): "<< samples.size() << endl;
for (int i = 0; i < 10; ++i)
{
cout << trans(vector_to_matrix(labels[i]));
cout << trans(vector_to_matrix(samples[i]));
cout << "******************************" << endl;
}
structural_sequence_labeling_trainer<feature_extractor> trainer;
trainer.set_c(1000);
trainer.set_num_threads(4);
//trainer.be_verbose();
//sequence_labeler<feature_extractor> labeler = trainer.train(samples, labels);
//cout << labeler.get_weights() << endl;
matrix<double> cm;
cm = cross_validate_sequence_labeler(trainer, samples, labels, 4);
//cm = test_sequence_labeler(labeler, samples, labels);
cout << cm << endl;
cout << "label accuracy: "<< sum(diag(cm))/sum(cm) << endl;
matrix<double,0,1> true_hmm_model_weights = log(join_cols(reshape_to_column_vector(transition_probabilities),
reshape_to_column_vector(emission_probabilities)));
sequence_labeler<feature_extractor> labeler_true(feature_extractor(), true_hmm_model_weights);
cout << endl;
cm = test_sequence_labeler(labeler_true, samples, labels);
cout << cm << endl;
cout << "label accuracy: "<< sum(diag(cm))/sum(cm) << endl;
}
// ----------------------------------------------------------------------------------------
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