public virtual ClassicCounter <L> ScoresOf(RVFDatum <L, F> example)
{
ClassicCounter <L> scores = new ClassicCounter <L>();
Counters.AddInPlace(scores, priors);
if (addZeroValued)
{
Counters.AddInPlace(scores, priorZero);
}
foreach (L l in labels)
{
double score = 0.0;
ICounter <F> features = example.AsFeaturesCounter();
foreach (F f in features.KeySet())
{
int value = (int)features.GetCount(f);
score += Weight(l, f, int.Parse(value));
if (addZeroValued)
{
score -= Weight(l, f, zero);
}
}
scores.IncrementCount(l, score);
}
return(scores);
}
public virtual RVFDatum <L, F> ScaleDatumGaussian(RVFDatum <L, F> datum)
{
// scale this dataset before scaling the datum
if (means == null || stdevs == null)
{
ScaleFeaturesGaussian();
}
ICounter <F> scaledFeatures = new ClassicCounter <F>();
foreach (F feature in datum.AsFeatures())
{
int fID = this.featureIndex.IndexOf(feature);
if (fID >= 0)
{
double oldVal = datum.AsFeaturesCounter().GetCount(feature);
double newVal;
if (stdevs[fID] != 0)
{
newVal = (oldVal - means[fID]) / stdevs[fID];
}
else
{
newVal = oldVal;
}
scaledFeatures.IncrementCount(feature, newVal);
}
}
return(new RVFDatum <L, F>(scaledFeatures, datum.Label()));
}
/// <summary>The examples are assumed to be a list of RFVDatum.</summary>
/// <remarks>
/// The examples are assumed to be a list of RFVDatum.
/// The datums are assumed to not contain the zeroes and then they are added to each instance.
/// </remarks>
public virtual NaiveBayesClassifier <L, F> TrainClassifier(GeneralDataset <L, F> examples, ICollection <F> featureSet)
{
int numFeatures = featureSet.Count;
int[][] data = new int[][] { };
int[] labels = new int[examples.Size()];
labelIndex = new HashIndex <L>();
featureIndex = new HashIndex <F>();
foreach (F feat in featureSet)
{
featureIndex.Add(feat);
}
for (int d = 0; d < examples.Size(); d++)
{
RVFDatum <L, F> datum = examples.GetRVFDatum(d);
ICounter <F> c = datum.AsFeaturesCounter();
foreach (F feature in c.KeySet())
{
int fNo = featureIndex.IndexOf(feature);
int value = (int)c.GetCount(feature);
data[d][fNo] = value;
}
labelIndex.Add(datum.Label());
labels[d] = labelIndex.IndexOf(datum.Label());
}
int numClasses = labelIndex.Size();
return(TrainClassifier(data, labels, numFeatures, numClasses, labelIndex, featureIndex));
}
private ICounter <L> ScoresOfRVFDatum(RVFDatum <L, F> example)
{
ICounter <F> features = example.AsFeaturesCounter();
double sum = ScoreOf(features);
ICounter <L> c = new ClassicCounter <L>();
c.SetCount(classes[0], -sum);
c.SetCount(classes[1], sum);
return(c);
}
// todo: Fix javadoc, have unit tested
/// <summary>Print SVM Light Format file.</summary>
/// <remarks>
/// Print SVM Light Format file.
/// The following comments are no longer applicable because I am
/// now printing out the exact labelID for each example. -Ramesh ([email protected]) 12/17/2009.
/// If the Dataset has more than 2 classes, then it
/// prints using the label index (+1) (for svm_struct). If it is 2 classes, then the labelIndex.get(0)
/// is mapped to +1 and labelIndex.get(1) is mapped to -1 (for svm_light).
/// </remarks>
public virtual void PrintSVMLightFormat(PrintWriter pw)
{
//assumes each data item has a few features on, and sorts the feature keys while collecting the values in a counter
// old comment:
// the following code commented out by Ramesh ([email protected]) 12/17/2009.
// why not simply print the exact id of the label instead of mapping to some values??
// new comment:
// mihai: we NEED this, because svm_light has special conventions not supported by default by our labels,
// e.g., in a multiclass setting it assumes that labels start at 1 whereas our labels start at 0 (08/31/2010)
string[] labelMap = MakeSvmLabelMap();
for (int i = 0; i < size; i++)
{
RVFDatum <L, F> d = GetRVFDatum(i);
ICounter <F> c = d.AsFeaturesCounter();
ClassicCounter <int> printC = new ClassicCounter <int>();
foreach (F f in c.KeySet())
{
printC.SetCount(featureIndex.IndexOf(f), c.GetCount(f));
}
int[] features = Sharpen.Collections.ToArray(printC.KeySet(), new int[printC.KeySet().Count]);
Arrays.Sort(features);
StringBuilder sb = new StringBuilder();
sb.Append(labelMap[labels[i]]).Append(' ');
// sb.append(labels[i]).append(' '); // commented out by mihai: labels[i] breaks svm_light conventions!
/* Old code: assumes that F is Integer....
*
* for (int f: features) {
* sb.append((f + 1)).append(":").append(c.getCount(f)).append(" ");
* }
*/
//I think this is what was meant (using printC rather than c), but not sure
// ~Sarah Spikes ([email protected])
foreach (int f_1 in features)
{
sb.Append((f_1 + 1)).Append(':').Append(printC.GetCount(f_1)).Append(' ');
}
pw.Println(sb.ToString());
}
}
/// <summary>
/// Given an instance to classify, scores and returns
/// score by class.
/// </summary>
/// <remarks>
/// Given an instance to classify, scores and returns
/// score by class.
/// NOTE: supports only RVFDatums
/// </remarks>
public virtual ClassicCounter <K> ScoresOf(IDatum <K, V> datum)
{
if (datum is RVFDatum <object, object> )
{
RVFDatum <K, V> vec = (RVFDatum <K, V>)datum;
if (l2Normalize)
{
ClassicCounter <V> featVec = new ClassicCounter <V>(vec.AsFeaturesCounter());
Counters.Normalize(featVec);
vec = new RVFDatum <K, V>(featVec);
}
ClassicCounter <ICounter <V> > scores = new ClassicCounter <ICounter <V> >();
foreach (ICounter <V> instance in instances.AllValues())
{
scores.SetCount(instance, Counters.Cosine(vec.AsFeaturesCounter(), instance));
}
// set entry, for given instance and score
IList <ICounter <V> > sorted = Counters.ToSortedList(scores);
ClassicCounter <K> classScores = new ClassicCounter <K>();
for (int i = 0; i < k && i < sorted.Count; i++)
{
K label = classLookup[sorted[i]];
double count = 1.0;
if (weightedVotes)
{
count = scores.GetCount(sorted[i]);
}
classScores.IncrementCount(label, count);
}
return(classScores);
}
else
{
return(null);
}
}
public virtual double ProbabilityOfTrue(RVFDatum <bool, string> datum)
{
return(ProbabilityOfTrue(datum.AsFeaturesCounter()));
}
private double ProbabilityOfRVFDatum(RVFDatum <L, F> example)
{
return(ProbabilityOf(example.AsFeaturesCounter(), example.Label()));
}
private L ClassOfRVFDatum(RVFDatum <L, F> example)
{
return(ClassOf(example.AsFeaturesCounter()));
}
public virtual L ClassOf(RVFDatum <L, F> example)
{
//use classOf(Datum) instead.
return(ClassOf(example.AsFeaturesCounter()));
}
