summaryrefslogtreecommitdiffstats
path: root/ml/dlib/examples/krr_classification_ex.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'ml/dlib/examples/krr_classification_ex.cpp')
-rw-r--r--ml/dlib/examples/krr_classification_ex.cpp205
1 files changed, 0 insertions, 205 deletions
diff --git a/ml/dlib/examples/krr_classification_ex.cpp b/ml/dlib/examples/krr_classification_ex.cpp
deleted file mode 100644
index 42648351f..000000000
--- a/ml/dlib/examples/krr_classification_ex.cpp
+++ /dev/null
@@ -1,205 +0,0 @@
-// The contents of this file are in the public domain. See LICENSE_FOR_EXAMPLE_PROGRAMS.txt
-/*
-
- This is an example illustrating the use of the kernel ridge regression
- object from the dlib C++ Library.
-
- This example creates a simple set of data to train on and then shows
- you how to use the kernel ridge regression tool to find a good decision
- function that can classify examples in our data set.
-
-
- The data used in this example will be 2 dimensional data and will
- come from a distribution where points with a distance less than 13
- from the origin are labeled +1 and all other points are labeled
- as -1. All together, the dataset will contain 10201 sample points.
-
-*/
-
-
-#include <iostream>
-#include <dlib/svm.h>
-
-using namespace std;
-using namespace dlib;
-
-
-int main()
-{
- // This typedef declares a matrix with 2 rows and 1 column. It will be the
- // object that contains each of our 2 dimensional samples. (Note that if you wanted
- // more than 2 features in this vector you can simply change the 2 to something else.
- // Or if you don't know how many features you want until runtime then you can put a 0
- // here and use the matrix.set_size() member function)
- typedef matrix<double, 2, 1> sample_type;
-
- // This is a typedef for the type of kernel we are going to use in this example.
- // In this case I have selected the radial basis kernel that can operate on our
- // 2D sample_type objects
- typedef radial_basis_kernel<sample_type> kernel_type;
-
-
- // Now we make objects to contain our samples and their respective labels.
- std::vector<sample_type> samples;
- std::vector<double> labels;
-
- // Now let's put some data into our samples and labels objects. We do this
- // by looping over a bunch of points and labeling them according to their
- // distance from the origin.
- for (double r = -20; r <= 20; r += 0.4)
- {
- for (double c = -20; c <= 20; c += 0.4)
- {
- sample_type samp;
- samp(0) = r;
- samp(1) = c;
- samples.push_back(samp);
-
- // if this point is less than 13 from the origin
- if (sqrt((double)r*r + c*c) <= 13)
- labels.push_back(+1);
- else
- labels.push_back(-1);
-
- }
- }
-
- cout << "samples generated: " << samples.size() << endl;
- cout << " number of +1 samples: " << sum(mat(labels) > 0) << endl;
- cout << " number of -1 samples: " << sum(mat(labels) < 0) << endl;
-
- // Here we normalize all the samples by subtracting their mean and dividing by their standard deviation.
- // This is generally a good idea since it often heads off numerical stability problems and also
- // prevents one large feature from smothering others. Doing this doesn't matter much in this example
- // so I'm just doing this here so you can see an easy way to accomplish this with
- // the library.
- vector_normalizer<sample_type> normalizer;
- // let the normalizer learn the mean and standard deviation of the samples
- normalizer.train(samples);
- // now normalize each sample
- for (unsigned long i = 0; i < samples.size(); ++i)
- samples[i] = normalizer(samples[i]);
-
-
- // here we make an instance of the krr_trainer object that uses our kernel type.
- krr_trainer<kernel_type> trainer;
-
- // The krr_trainer has the ability to perform leave-one-out cross-validation.
- // It does this to automatically determine the regularization parameter. Since
- // we are performing classification instead of regression we should be sure to
- // call use_classification_loss_for_loo_cv(). This function tells it to measure
- // errors in terms of the number of classification mistakes instead of mean squared
- // error between decision function output values and labels.
- trainer.use_classification_loss_for_loo_cv();
-
-
- // Now we loop over some different gamma values to see how good they are.
- cout << "\ndoing leave-one-out cross-validation" << endl;
- for (double gamma = 0.000001; gamma <= 1; gamma *= 5)
- {
- // tell the trainer the parameters we want to use
- trainer.set_kernel(kernel_type(gamma));
-
- // loo_values will contain the LOO predictions for each sample. In the case
- // of perfect prediction it will end up being a copy of labels.
- std::vector<double> loo_values;
- trainer.train(samples, labels, loo_values);
-
- // Print gamma and the fraction of samples correctly classified during LOO cross-validation.
- const double classification_accuracy = mean_sign_agreement(labels, loo_values);
- cout << "gamma: " << gamma << " LOO accuracy: " << classification_accuracy << endl;
- }
-
-
- // From looking at the output of the above loop it turns out that a good value for
- // gamma for this problem is 0.000625. So that is what we will use.
- trainer.set_kernel(kernel_type(0.000625));
- typedef decision_function<kernel_type> dec_funct_type;
- typedef normalized_function<dec_funct_type> funct_type;
-
-
- // Here we are making an instance of the normalized_function object. This object provides a convenient
- // way to store the vector normalization information along with the decision function we are
- // going to learn.
- funct_type learned_function;
- learned_function.normalizer = normalizer; // save normalization information
- learned_function.function = trainer.train(samples, labels); // perform the actual training and save the results
-
- // print out the number of basis vectors in the resulting decision function
- cout << "\nnumber of basis vectors in our learned_function is "
- << learned_function.function.basis_vectors.size() << endl;
-
- // Now let's try this decision_function on some samples we haven't seen before.
- // The decision function will return values >= 0 for samples it predicts
- // are in the +1 class and numbers < 0 for samples it predicts to be in the -1 class.
- sample_type sample;
-
- sample(0) = 3.123;
- sample(1) = 2;
- cout << "This is a +1 class example, the classifier output is " << learned_function(sample) << endl;
-
- sample(0) = 3.123;
- sample(1) = 9.3545;
- cout << "This is a +1 class example, the classifier output is " << learned_function(sample) << endl;
-
- sample(0) = 13.123;
- sample(1) = 9.3545;
- cout << "This is a -1 class example, the classifier output is " << learned_function(sample) << endl;
-
- sample(0) = 13.123;
- sample(1) = 0;
- cout << "This is a -1 class example, the classifier output is " << learned_function(sample) << endl;
-
-
- // We can also train a decision function that reports a well conditioned probability
- // instead of just a number > 0 for the +1 class and < 0 for the -1 class. An example
- // of doing that follows:
- typedef probabilistic_decision_function<kernel_type> probabilistic_funct_type;
- typedef normalized_function<probabilistic_funct_type> pfunct_type;
-
- // The train_probabilistic_decision_function() is going to perform 3-fold cross-validation.
- // So it is important that the +1 and -1 samples be distributed uniformly across all the folds.
- // calling randomize_samples() will make sure that is the case.
- randomize_samples(samples, labels);
-
- pfunct_type learned_pfunct;
- learned_pfunct.normalizer = normalizer;
- learned_pfunct.function = train_probabilistic_decision_function(trainer, samples, labels, 3);
- // Now we have a function that returns the probability that a given sample is of the +1 class.
-
- // print out the number of basis vectors in the resulting decision function.
- // (it should be the same as in the one above)
- cout << "\nnumber of basis vectors in our learned_pfunct is "
- << learned_pfunct.function.decision_funct.basis_vectors.size() << endl;
-
- sample(0) = 3.123;
- sample(1) = 2;
- cout << "This +1 class example should have high probability. Its probability is: "
- << learned_pfunct(sample) << endl;
-
- sample(0) = 3.123;
- sample(1) = 9.3545;
- cout << "This +1 class example should have high probability. Its probability is: "
- << learned_pfunct(sample) << endl;
-
- sample(0) = 13.123;
- sample(1) = 9.3545;
- cout << "This -1 class example should have low probability. Its probability is: "
- << learned_pfunct(sample) << endl;
-
- sample(0) = 13.123;
- sample(1) = 0;
- cout << "This -1 class example should have low probability. Its probability is: "
- << learned_pfunct(sample) << endl;
-
-
-
- // Another thing that is worth knowing is that just about everything in dlib is serializable.
- // So for example, you can save the learned_pfunct object to disk and recall it later like so:
- serialize("saved_function.dat") << learned_pfunct;
-
- // Now let's open that file back up and load the function object it contains.
- deserialize("saved_function.dat") >> learned_pfunct;
-
-}
-