func findBestSplit(partition base.FixedDataGrid) {
var delta float64
delta = math.MinInt64
attrs := partition.AllAttributes()
classAttrs := partition.AllClassAttributes()
candidates := base.AttributeDifferenceReferences(attrs, classAttrs)
fmt.Println(delta)
fmt.Println(classAttrs)
fmt.Println(reflect.TypeOf(partition))
fmt.Println(reflect.TypeOf(candidates))
for i, n := range attrs {
fmt.Println(i)
//fmt.Println(partition)
fmt.Println(reflect.TypeOf(n))
attributeSpec, _ := partition.GetAttribute(n)
fmt.Println(partition.GetAttribute(n))
_, rows := partition.Size()
for j := 0; j < rows; j++ {
data := partition.Get(attributeSpec, j)
fmt.Println(base.UnpackBytesToFloat(data))
}
}
}
// GenerateSplitRule returns the best attribute out of those randomly chosen
// which maximises Information Gain
func (r *RandomTreeRuleGenerator) GenerateSplitRule(f base.FixedDataGrid) *DecisionTreeRule {
var consideredAttributes []base.Attribute
// First step is to generate the random attributes that we'll consider
allAttributes := base.AttributeDifferenceReferences(f.AllAttributes(), f.AllClassAttributes())
maximumAttribute := len(allAttributes)
attrCounter := 0
for {
if len(consideredAttributes) >= r.Attributes {
break
}
selectedAttrIndex := rand.Intn(maximumAttribute)
selectedAttribute := allAttributes[selectedAttrIndex]
matched := false
for _, a := range consideredAttributes {
if a.Equals(selectedAttribute) {
matched = true
break
}
}
if matched {
continue
}
consideredAttributes = append(consideredAttributes, selectedAttribute)
attrCounter++
}
return r.internalRule.GetSplitRuleFromSelection(consideredAttributes, f)
}
// GenerateSplitAttribute returns the non-class Attribute which maximises the
// information gain.
//
// IMPORTANT: passing a base.Instances with no Attributes other than the class
// variable will panic()
func (r *InformationGainRuleGenerator) GenerateSplitAttribute(f base.FixedDataGrid) base.Attribute {
attrs := f.AllAttributes()
classAttrs := f.AllClassAttributes()
candidates := base.AttributeDifferenceReferences(attrs, classAttrs)
return r.GetSplitAttributeFromSelection(candidates, f)
}
// GenerateSplitRule returns the non-class Attribute-based DecisionTreeRule
// which maximises the information gain.
//
// IMPORTANT: passing a base.Instances with no Attributes other than the class
// variable will panic()
func (g *GiniCoefficientRuleGenerator) GenerateSplitRule(f base.FixedDataGrid) *DecisionTreeRule {
attrs := f.AllAttributes()
classAttrs := f.AllClassAttributes()
candidates := base.AttributeDifferenceReferences(attrs, classAttrs)
return g.GetSplitRuleFromSelection(candidates, f)
}
// Predict outputs a base.Instances containing predictions from this tree
func (d *DecisionTreeNode) Predict(what base.FixedDataGrid) (base.FixedDataGrid, error) {
predictions := base.GeneratePredictionVector(what)
classAttr := getClassAttr(predictions)
classAttrSpec, err := predictions.GetAttribute(classAttr)
if err != nil {
panic(err)
}
predAttrs := base.AttributeDifferenceReferences(what.AllAttributes(), predictions.AllClassAttributes())
predAttrSpecs := base.ResolveAttributes(what, predAttrs)
what.MapOverRows(predAttrSpecs, func(row [][]byte, rowNo int) (bool, error) {
cur := d
for {
if cur.Children == nil {
predictions.Set(classAttrSpec, rowNo, classAttr.GetSysValFromString(cur.Class))
break
} else {
splitVal := cur.SplitRule.SplitVal
at := cur.SplitRule.SplitAttr
ats, err := what.GetAttribute(at)
if err != nil {
//predictions.Set(classAttrSpec, rowNo, classAttr.GetSysValFromString(cur.Class))
//break
panic(err)
}
var classVar string
if _, ok := ats.GetAttribute().(*base.FloatAttribute); ok {
// If it's a numeric Attribute (e.g. FloatAttribute) check that
// the value of the current node is greater than the old one
classVal := base.UnpackBytesToFloat(what.Get(ats, rowNo))
if classVal > splitVal {
classVar = "1"
} else {
classVar = "0"
}
} else {
classVar = ats.GetAttribute().GetStringFromSysVal(what.Get(ats, rowNo))
}
if next, ok := cur.Children[classVar]; ok {
cur = next
} else {
// Suspicious of this
var bestChild string
for c := range cur.Children {
bestChild = c
if c > classVar {
break
}
}
cur = cur.Children[bestChild]
}
}
}
return true, nil
})
return predictions, nil
}
// Predict outputs a base.Instances containing predictions from this tree
func (d *DecisionTreeNode) Predict(what base.FixedDataGrid) base.FixedDataGrid {
predictions := base.GeneratePredictionVector(what)
classAttr := getClassAttr(predictions)
classAttrSpec, err := predictions.GetAttribute(classAttr)
if err != nil {
panic(err)
}
predAttrs := base.AttributeDifferenceReferences(what.AllAttributes(), predictions.AllClassAttributes())
predAttrSpecs := base.ResolveAttributes(what, predAttrs)
what.MapOverRows(predAttrSpecs, func(row [][]byte, rowNo int) (bool, error) {
cur := d
for {
if cur.Children == nil {
predictions.Set(classAttrSpec, rowNo, classAttr.GetSysValFromString(cur.Class))
break
} else {
at := cur.SplitAttr
ats, err := what.GetAttribute(at)
if err != nil {
predictions.Set(classAttrSpec, rowNo, classAttr.GetSysValFromString(cur.Class))
break
}
classVar := ats.GetAttribute().GetStringFromSysVal(what.Get(ats, rowNo))
if next, ok := cur.Children[classVar]; ok {
cur = next
} else {
var bestChild string
for c := range cur.Children {
bestChild = c
if c > classVar {
break
}
}
cur = cur.Children[bestChild]
}
}
}
return true, nil
})
return predictions
}