// Predict is just a wrapper for the PredictOne function.
//
// IMPORTANT: Predict panics if Fit was not called or if the
// document vector and train matrix have a different number of columns.
func (nb *BernoulliNBClassifier) Predict(what base.FixedDataGrid) base.FixedDataGrid {
// Generate return vector
ret := base.GeneratePredictionVector(what)
// Get the features
featAttrSpecs := base.ResolveAttributes(what, nb.attrs)
what.MapOverRows(featAttrSpecs, func(row [][]byte, i int) (bool, error) {
base.SetClass(ret, i, nb.PredictOne(row))
return true, nil
})
return ret
}
// Predict returns a classification for the vector, based on a vector input, using the KNN algorithm.
func (KNN *KNNClassifier) Predict(what base.FixedDataGrid) base.FixedDataGrid {
// Check what distance function we are using
var distanceFunc pairwise.PairwiseDistanceFunc
switch KNN.DistanceFunc {
case "euclidean":
distanceFunc = pairwise.NewEuclidean()
case "manhattan":
distanceFunc = pairwise.NewManhattan()
default:
panic("unsupported distance function")
}
// Check Compatibility
allAttrs := base.CheckCompatible(what, KNN.TrainingData)
if allAttrs == nil {
// Don't have the same Attributes
return nil
}
// Remove the Attributes which aren't numeric
allNumericAttrs := make([]base.Attribute, 0)
for _, a := range allAttrs {
if fAttr, ok := a.(*base.FloatAttribute); ok {
allNumericAttrs = append(allNumericAttrs, fAttr)
}
}
// Generate return vector
ret := base.GeneratePredictionVector(what)
// Resolve Attribute specifications for both
whatAttrSpecs := base.ResolveAttributes(what, allNumericAttrs)
trainAttrSpecs := base.ResolveAttributes(KNN.TrainingData, allNumericAttrs)
// Reserve storage for most the most similar items
distances := make(map[int]float64)
// Reserve storage for voting map
maxmap := make(map[string]int)
// Reserve storage for row computations
trainRowBuf := make([]float64, len(allNumericAttrs))
predRowBuf := make([]float64, len(allNumericAttrs))
// Iterate over all outer rows
what.MapOverRows(whatAttrSpecs, func(predRow [][]byte, predRowNo int) (bool, error) {
// Read the float values out
for i, _ := range allNumericAttrs {
predRowBuf[i] = base.UnpackBytesToFloat(predRow[i])
}
predMat := utilities.FloatsToMatrix(predRowBuf)
// Find the closest match in the training data
KNN.TrainingData.MapOverRows(trainAttrSpecs, func(trainRow [][]byte, srcRowNo int) (bool, error) {
// Read the float values out
for i, _ := range allNumericAttrs {
trainRowBuf[i] = base.UnpackBytesToFloat(trainRow[i])
}
// Compute the distance
trainMat := utilities.FloatsToMatrix(trainRowBuf)
distances[srcRowNo] = distanceFunc.Distance(predMat, trainMat)
return true, nil
})
sorted := utilities.SortIntMap(distances)
values := sorted[:KNN.NearestNeighbours]
// Reset maxMap
for a := range maxmap {
maxmap[a] = 0
}
// Refresh maxMap
for _, elem := range values {
label := base.GetClass(KNN.TrainingData, elem)
if _, ok := maxmap[label]; ok {
maxmap[label]++
} else {
maxmap[label] = 1
}
}
// Sort the maxMap
var maxClass string
maxVal := -1
for a := range maxmap {
if maxmap[a] > maxVal {
maxVal = maxmap[a]
maxClass = a
}
}
base.SetClass(ret, predRowNo, maxClass)
return true, nil
})
return ret
}
// Predict gathers predictions from all the classifiers
// and outputs the most common (majority) class
//
// IMPORTANT: in the event of a tie, the first class which
// achieved the tie value is output.
func (b *BaggedModel) Predict(from base.FixedDataGrid) base.FixedDataGrid {
n := runtime.NumCPU()
// Channel to receive the results as they come in
votes := make(chan base.DataGrid, n)
// Count the votes for each class
voting := make(map[int](map[string]int))
// Create a goroutine to collect the votes
var votingwait sync.WaitGroup
votingwait.Add(1)
go func() {
for { // Need to resolve the voting problem
incoming, ok := <-votes
if ok {
cSpecs := base.ResolveAttributes(incoming, incoming.AllClassAttributes())
incoming.MapOverRows(cSpecs, func(row [][]byte, predRow int) (bool, error) {
// Check if we've seen this class before...
if _, ok := voting[predRow]; !ok {
// If we haven't, create an entry
voting[predRow] = make(map[string]int)
// Continue on the current row
}
voting[predRow][base.GetClass(incoming, predRow)]++
return true, nil
})
} else {
votingwait.Done()
break
}
}
}()
// Create workers to process the predictions
processpipe := make(chan int, n)
var processwait sync.WaitGroup
for i := 0; i < n; i++ {
processwait.Add(1)
go func() {
for {
if i, ok := <-processpipe; ok {
c := b.Models[i]
l := b.generatePredictionInstances(i, from)
votes <- c.Predict(l)
} else {
processwait.Done()
break
}
}
}()
}
// Send all the models to the workers for prediction
for i := range b.Models {
processpipe <- i
}
close(processpipe) // Finished sending models to be predicted
processwait.Wait() // Predictors all finished processing
close(votes) // Close the vote channel and allow it to drain
votingwait.Wait() // All the votes are in
// Generate the overall consensus
ret := base.GeneratePredictionVector(from)
for i := range voting {
maxClass := ""
maxCount := 0
// Find the most popular class
for c := range voting[i] {
votes := voting[i][c]
if votes > maxCount {
maxClass = c
maxCount = votes
}
}
base.SetClass(ret, i, maxClass)
}
return ret
}
// Predict returns a classification for the vector, based on a vector input, using the KNN algorithm.
func (KNN *KNNClassifier) Predict(what base.FixedDataGrid) base.FixedDataGrid {
// Check what distance function we are using
var distanceFunc pairwise.PairwiseDistanceFunc
switch KNN.DistanceFunc {
case "euclidean":
distanceFunc = pairwise.NewEuclidean()
case "manhattan":
distanceFunc = pairwise.NewManhattan()
default:
panic("unsupported distance function")
}
// Check Compatibility
allAttrs := base.CheckCompatible(what, KNN.TrainingData)
if allAttrs == nil {
// Don't have the same Attributes
return nil
}
// Use optimised version if permitted
if KNN.AllowOptimisations {
if KNN.DistanceFunc == "euclidean" {
if KNN.canUseOptimisations(what) {
return KNN.optimisedEuclideanPredict(what.(*base.DenseInstances))
}
}
}
fmt.Println("Optimisations are switched off")
// Remove the Attributes which aren't numeric
allNumericAttrs := make([]base.Attribute, 0)
for _, a := range allAttrs {
if fAttr, ok := a.(*base.FloatAttribute); ok {
allNumericAttrs = append(allNumericAttrs, fAttr)
}
}
// Generate return vector
ret := base.GeneratePredictionVector(what)
// Resolve Attribute specifications for both
whatAttrSpecs := base.ResolveAttributes(what, allNumericAttrs)
trainAttrSpecs := base.ResolveAttributes(KNN.TrainingData, allNumericAttrs)
// Reserve storage for most the most similar items
distances := make(map[int]float64)
// Reserve storage for voting map
maxmap := make(map[string]int)
// Reserve storage for row computations
trainRowBuf := make([]float64, len(allNumericAttrs))
predRowBuf := make([]float64, len(allNumericAttrs))
_, maxRow := what.Size()
curRow := 0
// Iterate over all outer rows
what.MapOverRows(whatAttrSpecs, func(predRow [][]byte, predRowNo int) (bool, error) {
if (curRow%1) == 0 && curRow > 0 {
fmt.Printf("KNN: %.2f %% done\n", float64(curRow)*100.0/float64(maxRow))
}
curRow++
// Read the float values out
for i, _ := range allNumericAttrs {
predRowBuf[i] = base.UnpackBytesToFloat(predRow[i])
}
predMat := utilities.FloatsToMatrix(predRowBuf)
// Find the closest match in the training data
KNN.TrainingData.MapOverRows(trainAttrSpecs, func(trainRow [][]byte, srcRowNo int) (bool, error) {
// Read the float values out
for i, _ := range allNumericAttrs {
trainRowBuf[i] = base.UnpackBytesToFloat(trainRow[i])
}
// Compute the distance
trainMat := utilities.FloatsToMatrix(trainRowBuf)
distances[srcRowNo] = distanceFunc.Distance(predMat, trainMat)
return true, nil
})
sorted := utilities.SortIntMap(distances)
values := sorted[:KNN.NearestNeighbours]
maxClass := KNN.vote(maxmap, values)
base.SetClass(ret, predRowNo, maxClass)
return true, nil
})
return ret
}
func (KNN *KNNClassifier) optimisedEuclideanPredict(d *base.DenseInstances) base.FixedDataGrid {
// Create return vector
ret := base.GeneratePredictionVector(d)
// Type-assert training data
tr := KNN.TrainingData.(*base.DenseInstances)
// Enumeration of AttributeGroups
agPos := make(map[string]int)
agTrain := tr.AllAttributeGroups()
agPred := d.AllAttributeGroups()
classAttrs := tr.AllClassAttributes()
counter := 0
for ag := range agTrain {
// Detect whether the AttributeGroup has any classes in it
attrs := agTrain[ag].Attributes()
//matched := false
if len(base.AttributeIntersect(classAttrs, attrs)) == 0 {
agPos[ag] = counter
}
counter++
}
// Pointers to the start of each prediction row
rowPointers := make([]*C.double, len(agPred))
trainPointers := make([]*C.double, len(agPred))
rowSizes := make([]int, len(agPred))
for ag := range agPred {
if ap, ok := agPos[ag]; ok {
rowPointers[ap] = (*C.double)(unsafe.Pointer(&(agPred[ag].Storage()[0])))
trainPointers[ap] = (*C.double)(unsafe.Pointer(&(agTrain[ag].Storage()[0])))
rowSizes[ap] = agPred[ag].RowSizeInBytes() / 8
}
}
_, predRows := d.Size()
_, trainRows := tr.Size()
// Crete the distance vector
distanceVec := distanceRecs(make([]_Ctype_struct_dist, trainRows))
// Additional datastructures
voteVec := make([]int, KNN.NearestNeighbours)
maxMap := make(map[string]int)
for row := 0; row < predRows; row++ {
for i := 0; i < trainRows; i++ {
distanceVec[i].dist = 0
}
for ag := range agPred {
if ap, ok := agPos[ag]; ok {
C.euclidean_distance(
&(distanceVec[0]),
C.int(trainRows),
C.int(len(agPred[ag].Attributes())),
C.int(row),
trainPointers[ap],
rowPointers[ap],
)
}
}
sort.Sort(distanceVec)
votes := distanceVec[:KNN.NearestNeighbours]
for i, v := range votes {
voteVec[i] = int(v.p)
}
maxClass := KNN.vote(maxMap, voteVec)
base.SetClass(ret, row, maxClass)
}
return ret
}
func main() {
// Instances can be read using ParseCsvToInstances
rawData, err := base.ParseCSVToInstances("../datasets/iris_headers.csv", true)
if err != nil {
panic(err)
}
// Instances can be printed, and you'll see a human-readable summary
// if you do so. The first section is a line like
// Instances with 150 row(s) and 5 attribute(s)
//
// It next prints all the attributes
// FloatAttribute(Sepal length)
// FloatAttribute(Sepal width)
// FloatAttribute(Petal length)
// FloatAttribute(Petal width)
// CategoricalAttribute([Iris-setosa Iris-versicolor Iris-viriginica])
// The final attribute has an asterisk (*) printed before it,
// meaning that it is the class variable. It then prints out up to
// 30 rows which correspond to those attributes.
// 5.10 3.50 1.40 0.20 Iris-setosa
// 4.90 3.00 1.40 0.20 Iris-setosa
fmt.Println(rawData)
// If two decimal places isn't enough, you can update the
// Precision field on any FloatAttribute
if attr, ok := rawData.AllAttributes()[0].(*base.FloatAttribute); !ok {
panic("Invalid cast")
} else {
attr.Precision = 4
}
// Now the first column has more precision
fmt.Println(rawData)
// We can update the set of Instances, although the API
// for doing so is not very sophisticated.
// First, have to resolve Attribute Specifications
as := base.ResolveAttributes(rawData, rawData.AllAttributes())
// Attribute Specifications describe where a given column lives
rawData.Set(as[0], 0, as[0].GetAttribute().GetSysValFromString("1.00"))
// A SetClass method exists as a shortcut
base.SetClass(rawData, 0, "Iris-unusual")
fmt.Println(rawData)
// There is a way of creating new Instances from scratch.
// Inside an Instance, everything's stored as float64
newData := make([]float64, 2)
newData[0] = 1.0
newData[1] = 0.0
// Let's create some attributes
attrs := make([]base.Attribute, 2)
attrs[0] = base.NewFloatAttribute("Arbitrary Float Quantity")
attrs[1] = new(base.CategoricalAttribute)
attrs[1].SetName("Class")
// Insert a standard class
attrs[1].GetSysValFromString("A")
// Now let's create the final instances set
newInst := base.NewDenseInstances()
// Add the attributes
newSpecs := make([]base.AttributeSpec, len(attrs))
for i, a := range attrs {
newSpecs[i] = newInst.AddAttribute(a)
}
// Allocate space
newInst.Extend(1)
// Write the data
newInst.Set(newSpecs[0], 0, newSpecs[0].GetAttribute().GetSysValFromString("1.0"))
newInst.Set(newSpecs[1], 0, newSpecs[1].GetAttribute().GetSysValFromString("A"))
fmt.Println(newInst)
}