svm_binary_classifier.py

#!/usr/bin/python
# The contents of this file are in the public domain. See LICENSE_FOR_EXAMPLE_PROGRAMS.txt
#
# 
# This is an example illustrating the use of a binary SVM classifier tool from
# the dlib C++ Library.  In this example, we will create a simple test dataset
# and show how to learn a classifier from it.  
#
#
# COMPILING/INSTALLING THE DLIB PYTHON INTERFACE
#   You can install dlib using the command:
#       pip install dlib
#
#   Alternatively, if you want to compile dlib yourself then go into the dlib
#   root folder and run:
#       python setup.py install
#   or
#       python setup.py install --yes USE_AVX_INSTRUCTIONS
#   if you have a CPU that supports AVX instructions, since this makes some
#   things run faster.  
#
#   Compiling dlib should work on any operating system so long as you have
#   CMake installed.  On Ubuntu, this can be done easily by running the
#   command:
#       sudo apt-get install cmake
#

import dlib
try:
    import cPickle as pickle
except ImportError:
    import pickle

x = dlib.vectors()
y = dlib.array()

# Make a training dataset.  Here we have just two training examples.  Normally
# you would use a much larger training dataset, but for the purpose of example
# this is plenty.  For binary classification, the y labels should all be either +1 or -1.
x.append(dlib.vector([1, 2, 3, -1, -2, -3]))
y.append(+1)

x.append(dlib.vector([-1, -2, -3, 1, 2, 3]))
y.append(-1)


# Now make a training object.  This object is responsible for turning a
# training dataset into a prediction model.  This one here is a SVM trainer
# that uses a linear kernel.  If you wanted to use a RBF kernel or histogram
# intersection kernel you could change it to one of these lines:
#  svm = dlib.svm_c_trainer_histogram_intersection()
#  svm = dlib.svm_c_trainer_radial_basis()
svm = dlib.svm_c_trainer_linear()
svm.be_verbose()
svm.set_c(10)

# Now train the model.  The return value is the trained model capable of making predictions.
classifier = svm.train(x, y)

# Now run the model on our data and look at the results.
print("prediction for first sample:  {}".format(classifier(x[0])))
print("prediction for second sample: {}".format(classifier(x[1])))


# classifier models can also be pickled in the same was as any other python object.
with open('saved_model.pickle', 'wb') as handle:
    pickle.dump(classifier, handle, 2)