func (stat *Stat) SetPrecisionFromRate(p, n int64) {
	stat.Precision = (stat.TPRate * float64(p)) /
		((stat.TPRate * float64(p)) + (stat.FPRate * float64(n)))
}
SetPrecisionFromRate will set Precision value using tprate and fprate.
`p` and `n` is the number of positive and negative class in samples.
package classifier
import (
	"time"
	"github.com/shuLhan/share/lib/dsv"
	"github.com/shuLhan/share/lib/tabula"
)
type Stat struct {
	ID int64
	StartTime int64
	EndTime int64
	ElapsedTime int64
	TP int64
	FP int64
	TN int64
	FN int64
	OobError float64
	OobErrorMean float64
	TPRate float64
	FPRate float64
	TNRate float64
	Precision float64
	FMeasure float64
	Accuracy float64
	AUC float64
}
func (stat *Stat) SetAUC(v float64) {
	stat.AUC = v
}
func (stat *Stat) SetTPRate(tp, p int64) {
	stat.TP = tp
	stat.TPRate = float64(tp) / float64(p)
}
func (stat *Stat) SetFPRate(fp, n int64) {
	stat.FP = fp
	stat.FPRate = float64(fp) / float64(n)
}