Performing a 10-fold cross validation
From Jstacs
Jump to navigationJump to search
//create a Sample for each class from the input data, using the DNA alphabet
Sample[] data = new Sample[2];
data[0] = new DNASample( args[0] );
//the length of our input sequences
int length = data[0].getElementLength();
data[1] = new Sample( new DNASample( args[1] ), length );
AlphabetContainer container = data[0].getAlphabetContainer();
//create a new PWM
BayesianNetworkModel pwm = new BayesianNetworkModel( new BayesianNetworkModelParameterSet(
//the alphabet and the length of the model:
container, length,
//the equivalent sample size to compute hyper-parameters
4,
//some identifier for the model
"my PWM",
//we want a PWM, which is an inhomogeneous Markov model (IMM) of order 0
ModelType.IMM, (byte) 0,
//we want to estimate the MAP-parameters
LearningType.ML_OR_MAP ) );
//create a new mixture model using 2 PWMs
MixtureModel mixPwms = new MixtureModel(
//the length of the mixture model
length,
//the two components, which are PWMs
new Model[]{pwm,pwm},
//the number of starts of the EM
10,
//the equivalent sample sizes
new double[]{pwm.getESS(),pwm.getESS()},
//the hyper-parameters to draw the initial sequence-specific component weights (hidden variables)
1,
//stopping criterion
new SmallDifferenceOfFunctionEvaluationsCondition(1E-6),
//parameterization of the model, LAMBDA complies with the
//parameterization by log-probabilities
Parameterization.LAMBDA);
//create a new inhomogeneous Markov model of order 3
BayesianNetworkModel mm = new BayesianNetworkModel(
new BayesianNetworkModelParameterSet( container, length, 256, "my iMM(3)", ModelType.IMM, (byte) 3, LearningType.ML_OR_MAP ) );
//create a new PWM scoring function
BayesianNetworkScoringFunction dPwm = new BayesianNetworkScoringFunction(
//the alphabet and the length of the scoring function
container, length,
//the equivalent sample size for the plug-in parameters
4,
//we use plug-in parameters
true,
//a PWM is an inhomogeneous Markov model of order 0
new InhomogeneousMarkov(0));
//create a new mixture scoring function
MixtureScoringFunction dMixPwms = new MixtureScoringFunction(
//the number of starts
2,
//we use plug-in parameters
true,
//the two components, which are PWMs
dPwm,dPwm);
//create a new scoring function that is an inhomogeneous Markov model of order 3
BayesianNetworkScoringFunction dMm = new BayesianNetworkScoringFunction(container, length, 4, true, new InhomogeneousMarkov(3));
//create the classifiers
int threads = AbstractMultiThreadedOptimizableFunction.getNumberOfAvailableProcessors();
AbstractScoreBasedClassifier[] classifiers = new AbstractScoreBasedClassifier[]{
//model based with mixture model and Markov model
new ModelBasedClassifier( mixPwms, mm ),
//conditional likelihood based classifier
new MSPClassifier( new GenDisMixClassifierParameterSet(container, length,
//method for optimizing the conditional likelihood and
//other parameters of the numerical optimization
Optimizer.QUASI_NEWTON_BFGS, 1E-2, 1E-2, 1, true, KindOfParameter.PLUGIN, false, threads),
//mixture scoring function and Markov model scoring function
dMixPwms,dMm )
};
//create an new k-fold cross validation using above classifiers
KFoldCrossValidation cv = new KFoldCrossValidation( classifiers );
//we use a specificity of 0.999 to compute the sensitivity and a sensitivity of 0.95 to compute FPR and PPV
MeasureParameters mp = new MeasureParameters(false, 0.999, 0.95, 0.95);
//we do a 10-fold cross validation and partition the data by means of the number of symbols
KFoldCVAssessParameterSet cvpars = new KFoldCVAssessParameterSet(PartitionMethod.PARTITION_BY_NUMBER_OF_SYMBOLS, length, true, 10);
//compute the result of the cross validation and print them to System.out
System.out.println( cv.assess( mp, cvpars, data ) );