/**
* <p><b>Note: The streams are NOT closed</b></p>
*/
public static void doPredict(StreamReader reader, StreamWriter writer, Model model) {
int correct = 0;
int total = 0;
double error = 0;
double sump = 0, sumt = 0, sumpp = 0, sumtt = 0, sumpt = 0;
int nr_class = model.getNrClass();
double[] prob_estimates = null;
int n;
int nr_feature = model.getNrFeature();
if (model.bias >= 0)
n = nr_feature + 1;
else
n = nr_feature;
if (flag_predict_probability && !model.isProbabilityModel()) {
throw new ArgumentException("probability output is only supported for logistic regression");
}
if (flag_predict_probability) {
int[] labels = model.getLabels();
prob_estimates = new double[nr_class];
writer.Write("labels");
for (int j = 0; j < nr_class; j++)
writer.Write(" {0}", labels[j]);
writer.WriteLine();
}
String line = null;
while ((line = reader.ReadLine()) != null) {
List<Feature> x = new List<Feature>();
string[] parts = line.Split(new[]{' ', '\t'}, StringSplitOptions.RemoveEmptyEntries);
double target_label;
if (parts.Length == 0)
{
throw new InvalidOperationException("Wrong input format at line " + (total + 1));
}
String label = parts[0];
target_label = Linear.atof(label);
foreach (var token in parts.Skip(1))
{
string[] split = token.Split(':');
if (split.Length < 2) {
throw new InvalidOperationException("Wrong input format at line " + (total + 1));
}
try {
int idx = Linear.atoi(split[0]);
double val = Linear.atof(split[1]);
// feature indices larger than those in training are not used
if (idx <= nr_feature) {
Feature node = new Feature(idx, val);
x.Add(node);
}
} catch (FormatException e) {
throw new InvalidOperationException("Wrong input format at line " + (total + 1), e);
}
}
if (model.bias >= 0) {
Feature node = new Feature(n, model.bias);
x.Add(node);
}
Feature[] nodes = x.ToArray();
double predict_label;
if (flag_predict_probability) {
Debug.Assert(prob_estimates != null);
predict_label = Linear.predictProbability(model, nodes, prob_estimates);
Console.Write(predict_label);
for (int j = 0; j < model.nr_class; j++)
Console.Write(" {0}", prob_estimates[j]);
Console.WriteLine();
} else {
predict_label = Linear.predict(model, nodes);
Console.WriteLine("{0}", predict_label);
}
if (predict_label == target_label) {
++correct;
}
error += (predict_label - target_label) * (predict_label - target_label);
sump += predict_label;
sumt += target_label;
sumpp += predict_label * predict_label;
sumtt += target_label * target_label;
sumpt += predict_label * target_label;
++total;
}
if (model.solverType.isSupportVectorRegression()) //
{
Linear.info("Mean squared error = {0} (regression)", error / total);
Linear.info("Squared correlation coefficient = {0} (regression)", //
((total * sumpt - sump * sumt) * (total * sumpt - sump * sumt)) / ((total * sumpp - sump * sump) * (total * sumtt - sumt * sumt)));
} else {
Linear.info("Accuracy = {0} ({1}/{2})", (double)correct / total * 100, correct, total);
}
}
public bool Equals(Feature other)
{
if (ReferenceEquals(null, other)) return false;
if (ReferenceEquals(this, other)) return true;
return other.Index == Index && other.Value.Equals(Value);
}
/**
* reads a problem from LibSVM format
* @param file the SVM file
* @throws IOException obviously in case of any I/O exception ;)
* @throws InvalidInputDataException if the input file is not correctly formatted
*/
public static Problem readProblem(FileInfo file, double bias) {
using (StreamReader fp = new StreamReader(File.OpenRead(file.FullName)))
{
List<Double> vy = new List<Double>();
List<Feature[]> vx = new List<Feature[]>();
int max_index = 0;
int lineNr = 0;
while (true) {
String line = fp.ReadLine();
if (line == null) break;
lineNr++;
var tokens = line.Split(new[]{' ', '\t', '\f', ':'}, StringSplitOptions.RemoveEmptyEntries);
if (tokens.Length == 0) {
throw new InvalidInputDataException("empty line", file, lineNr);
}
try {
vy.Add(Linear.atof(tokens[0]));
} catch (FormatException e) {
throw new InvalidInputDataException("invalid label: " + tokens[0], file, lineNr, e);
}
tokens = tokens.Skip(1).ToArray();
int m = tokens.Length / 2;
Feature[] x;
if (bias >= 0) {
x = new Feature[m + 1];
} else {
x = new Feature[m];
}
int indexBefore = 0;
for (int j = 0; j < m; j++) {
var token = tokens[j * 2];
int index;
try {
index = Linear.atoi(token);
} catch (FormatException e) {
throw new InvalidInputDataException("invalid index: " + token, file, lineNr, e);
}
// assert that indices are valid and sorted
if (index < 0) throw new InvalidInputDataException("invalid index: " + index, file, lineNr);
if (index <= indexBefore) throw new InvalidInputDataException("indices must be sorted in ascending order", file, lineNr);
indexBefore = index;
token = tokens[j * 2 + 1];
try {
double value = Linear.atof(token);
x[j] = new Feature(index, value);
} catch (FormatException) {
throw new InvalidInputDataException("invalid value: " + token, file, lineNr);
}
}
if (m > 0) {
max_index = Math.Max(max_index, x[m - 1].Index);
}
vx.Add(x);
}
return constructProblem(vy, vx, max_index, bias);
}
}
public static double predictValues(Model model, Feature[] x, double[] dec_values)
{
int n;
if (model.bias >= 0)
n = model.nr_feature + 1;
else
n = model.nr_feature;
double[] w = model.w;
int nr_w;
if (model.nr_class == 2 && model.solverType.getId() != SolverType.MCSVM_CS)
nr_w = 1;
else
nr_w = model.nr_class;
for (int i = 0; i < nr_w; i++)
dec_values[i] = 0;
foreach (Feature lx in x)
{
int idx = lx.Index;
// the dimension of testing data may exceed that of training
if (idx <= n)
{
for (int i = 0; i < nr_w; i++)
{
dec_values[i] += w[(idx - 1) * nr_w + i] * lx.Value;
}
}
}
if (model.nr_class == 2)
{
if (model.solverType.isSupportVectorRegression())
return dec_values[0];
else
return (dec_values[0] > 0) ? model.label[0] : model.label[1];
}
else
{
int dec_max_idx = 0;
for (int i = 1; i < model.nr_class; i++)
{
if (dec_values[i] > dec_values[dec_max_idx]) dec_max_idx = i;
}
return model.label[dec_max_idx];
}
}
/**
* @throws IllegalArgumentException if model is not probabilistic (see {@link Model#isProbabilityModel()})
*/
public static double predictProbability(Model model, Feature[] x, double[] prob_estimates)
{
if (!model.isProbabilityModel())
{
StringBuilder sb = new StringBuilder("probability output is only supported for logistic regression");
sb.Append(". This is currently only supported by the following solvers: ");
int i = 0;
foreach (SolverType solverType in SolverType.values())
{
if (solverType.isLogisticRegressionSolver())
{
if (i++ > 0)
{
sb.Append(", ");
}
sb.Append(solverType.Name);
}
}
throw new ArgumentException(sb.ToString());
}
int nr_class = model.nr_class;
int nr_w;
if (nr_class == 2)
nr_w = 1;
else
nr_w = nr_class;
double label = predictValues(model, x, prob_estimates);
for (int i = 0; i < nr_w; i++)
prob_estimates[i] = 1 / (1 + Math.Exp(-prob_estimates[i]));
if (nr_class == 2) // for binary classification
prob_estimates[1] = 1.0 - prob_estimates[0];
else
{
double sum = 0;
for (int i = 0; i < nr_class; i++)
sum += prob_estimates[i];
for (int i = 0; i < nr_class; i++)
prob_estimates[i] = prob_estimates[i] / sum;
}
return label;
}
public static double predict(Model model, Feature[] x)
{
double[] dec_values = new double[model.nr_class];
return predictValues(model, x, dec_values);
}
/**
* @throws IllegalArgumentException if the feature nodes of prob are not sorted in ascending order
*/
public static Model train(Problem prob, Parameter param)
{
if (prob == null) throw new ArgumentNullException("problem must not be null");
if (param == null) throw new ArgumentNullException("parameter must not be null");
if (prob.n == 0) throw new ArgumentNullException("problem has zero features");
if (prob.l == 0) throw new ArgumentNullException("problem has zero instances");
foreach (Feature[] nodes in prob.x)
{
int indexBefore = 0;
foreach (Feature n_ in nodes)
{
if (n_.Index <= indexBefore)
{
throw new ArgumentException("feature nodes must be sorted by index in ascending order");
}
indexBefore = n_.Index;
}
}
int l = prob.l;
int n = prob.n;
int w_size = prob.n;
Model model = new Model();
if (prob.bias >= 0)
model.nr_feature = n - 1;
else
model.nr_feature = n;
model.solverType = param.solverType;
model.bias = prob.bias;
if (param.solverType.getId() == SolverType.L2R_L2LOSS_SVR || //
param.solverType.getId() == SolverType.L2R_L1LOSS_SVR_DUAL || //
param.solverType.getId() == SolverType.L2R_L2LOSS_SVR_DUAL)
{
model.w = new double[w_size];
model.nr_class = 2;
model.label = null;
checkProblemSize(n, model.nr_class);
train_one(prob, param, model.w, 0, 0);
}
else
{
int[] perm = new int[l];
// group training data of the same class
GroupClassesReturn rv = groupClasses(prob, perm);
int nr_class = rv.nr_class;
int[] label = rv.label;
int[] start = rv.start;
int[] count = rv.count;
checkProblemSize(n, nr_class);
model.nr_class = nr_class;
model.label = new int[nr_class];
for (int i = 0; i < nr_class; i++)
model.label[i] = label[i];
// calculate weighted C
double[] weighted_C = new double[nr_class];
for (int i = 0; i < nr_class; i++)
weighted_C[i] = param.C;
for (int i = 0; i < param.getNumWeights(); i++)
{
int j;
for (j = 0; j < nr_class; j++)
if (param.weightLabel[i] == label[j]) break;
if (j == nr_class) throw new ArgumentException("class label " + param.weightLabel[i] + " specified in weight is not found");
weighted_C[j] *= param.weight[i];
}
// constructing the subproblem
Feature[][] x = new Feature[l][];
for (int i = 0; i < l; i++)
x[i] = prob.x[perm[i]];
Problem sub_prob = new Problem();
sub_prob.l = l;
sub_prob.n = n;
sub_prob.x = new Feature[sub_prob.l][];
sub_prob.y = new double[sub_prob.l];
for (int k = 0; k < sub_prob.l; k++)
sub_prob.x[k] = x[k];
// multi-class svm by Crammer and Singer
if (param.solverType.getId() == SolverType.MCSVM_CS)
{
model.w = new double[n * nr_class];
for (int i = 0; i < nr_class; i++)
{
for (int j = start[i]; j < start[i] + count[i]; j++)
{
sub_prob.y[j] = i;
}
}
SolverMCSVM_CS solver = new SolverMCSVM_CS(sub_prob, nr_class, weighted_C, param.eps);
solver.solve(model.w);
}
else
{
if (nr_class == 2)
{
model.w = new double[w_size];
int e0 = start[0] + count[0];
int k = 0;
for (; k < e0; k++)
sub_prob.y[k] = +1;
for (; k < sub_prob.l; k++)
sub_prob.y[k] = -1;
train_one(sub_prob, param, model.w, weighted_C[0], weighted_C[1]);
}
else
{
model.w = new double[w_size * nr_class];
double[] w = new double[w_size];
for (int i = 0; i < nr_class; i++)
{
int si = start[i];
int ei = si + count[i];
int k = 0;
for (; k < si; k++)
sub_prob.y[k] = -1;
for (; k < ei; k++)
sub_prob.y[k] = +1;
for (; k < sub_prob.l; k++)
sub_prob.y[k] = -1;
train_one(sub_prob, param, w, weighted_C[i], param.C);
for (int j = 0; j < n; j++)
model.w[j * nr_class + i] = w[j];
}
}
}
}
return model;
}
