private static void RunFeaturesTest()
{
// this usually requires that the library script to update train.w or its moral equivalent needs to have been run
IntPtr vw = VowpalWabbitInterface.Initialize("-q st --noconstant --quiet");
IntPtr example = VowpalWabbitInterface.ReadExample(vw, "1 |s p^the_man w^the w^man |t p^un_homme w^un w^homme");
float score = VowpalWabbitInterface.Learn(vw, example);
VowpalWabbitInterface.FinishExample(vw, example);
VowpalWabbitInterface.FEATURE_SPACE[] featureSpace = new VowpalWabbitInterface.FEATURE_SPACE[2]; //maximum number of index spaces
VowpalWabbitInterface.FEATURE[] sfeatures = new VowpalWabbitInterface.FEATURE[3]; // the maximum number of features
VowpalWabbitInterface.FEATURE[] tfeatures = new VowpalWabbitInterface.FEATURE[3]; // the maximum number of features
GCHandle pinnedsFeatures = GCHandle.Alloc(sfeatures, GCHandleType.Pinned);
GCHandle pinnedtFeatures = GCHandle.Alloc(tfeatures, GCHandleType.Pinned);
featureSpace[0].features = pinnedsFeatures.AddrOfPinnedObject();
featureSpace[1].features = pinnedtFeatures.AddrOfPinnedObject();
GCHandle pinnedFeatureSpace = GCHandle.Alloc(featureSpace, GCHandleType.Pinned);
IntPtr featureSpacePtr = pinnedFeatureSpace.AddrOfPinnedObject();
uint snum = VowpalWabbitInterface.HashSpace(vw, "s");
featureSpace[0].name = (byte)'s';
sfeatures[0].weight_index = VowpalWabbitInterface.HashFeature(vw, "p^the_man", snum);
sfeatures[0].x = 1;
// add the character "delta" to test unicode
// do it as a string to test the marshaling is doing pinning correctly.
const string s = "w^thew^man\u0394";
sfeatures[1].weight_index = VowpalWabbitInterface.HashFeature(vw, s, snum);
sfeatures[1].x = 1;
sfeatures[2].weight_index = VowpalWabbitInterface.HashFeature(vw, "w^man", snum);
sfeatures[2].x = 1;
featureSpace[0].len = 3;
uint tnum = VowpalWabbitInterface.HashSpace(vw, "t");
featureSpace[1].name = (byte)'t';
tfeatures[0].weight_index = VowpalWabbitInterface.HashFeature(vw, "p^un_homme", tnum);
tfeatures[0].x = 1;
tfeatures[1].weight_index = VowpalWabbitInterface.HashFeature(vw, "w^un", tnum);
tfeatures[1].x = 1;
tfeatures[2].weight_index = VowpalWabbitInterface.HashFeature(vw, "w^homme", tnum);
tfeatures[2].x = 1;
featureSpace[1].len = 3;
IntPtr importedExample = VowpalWabbitInterface.ImportExample(vw, featureSpacePtr, featureSpace.Length);
VowpalWabbitInterface.AddLabel(importedExample, 1);
score = VowpalWabbitInterface.Learn(vw, importedExample);
Console.Error.WriteLine("p2 = {0}", score);
VowpalWabbitInterface.Finish(vw);
// clean up the memory we allocated
pinnedsFeatures.Free();
pinnedtFeatures.Free();
pinnedFeatureSpace.Free();
}