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helpers.go
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/
helpers.go
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package steps
import (
"bufio"
"bytes"
"math"
"github.com/antongulenko/go-onlinestats"
"github.com/bitflow-stream/go-bitflow/bitflow"
"gonum.org/v1/gonum/mat"
)
func ValuesToVector(input []bitflow.Value) []float64 {
values := make([]float64, len(input))
for i, val := range input {
values[i] = float64(val)
}
return values
}
func SampleToVector(sample *bitflow.Sample) []float64 {
return ValuesToVector(sample.Values)
}
func FillSample(s *bitflow.Sample, values []float64) {
s.Resize(len(values))
for i, val := range values {
s.Values[i] = bitflow.Value(val)
}
}
func AppendToSample(s *bitflow.Sample, values []float64) {
oldValues := s.Values
l := len(s.Values)
if !s.Resize(l + len(values)) {
copy(s.Values, oldValues)
}
for i, val := range values {
s.Values[l+i] = bitflow.Value(val)
}
}
func IsValidNumber(val float64) bool {
return !math.IsNaN(val) && !math.IsInf(val, 0)
}
func FillSampleFromMatrix(s *bitflow.Sample, row int, mat *mat.Dense) {
FillSample(s, mat.RawRowView(row))
}
func FillSamplesFromMatrix(s []*bitflow.Sample, mat *mat.Dense) {
for i, sample := range s {
FillSampleFromMatrix(sample, i, mat)
}
}
const _nul = rune(0)
func SplitShellCommand(s string) []string {
scanner := bufio.NewScanner(bytes.NewBuffer([]byte(s)))
scanner.Split(bufio.ScanRunes)
var res []string
var buf bytes.Buffer
quote := _nul
for scanner.Scan() {
r := rune(scanner.Text()[0])
flush := false
switch quote {
case _nul:
switch r {
case ' ', '\t', '\r', '\n':
flush = true
case '"', '\'':
quote = r
flush = true
}
case '"', '\'':
if r == quote {
flush = true
quote = _nul
}
}
if flush {
if buf.Len() > 0 {
res = append(res, buf.String())
buf.Reset()
}
} else {
buf.WriteRune(r)
}
}
// Un-closed quotes are ignored
if buf.Len() > 0 {
res = append(res, buf.String())
}
return res
}
type FeatureStats struct {
onlinestats.Running
Min float64
Max float64
}
func NewFeatureStats() *FeatureStats {
return &FeatureStats{
Min: math.MaxFloat64,
Max: -math.MaxFloat64,
}
}
func (stats *FeatureStats) Push(values ...float64) {
for _, value := range values {
stats.Running.Push(value)
stats.Min = math.Min(stats.Min, value)
stats.Max = math.Max(stats.Max, value)
}
}
func (stats *FeatureStats) ScaleMinMax(val float64, outputMin, outputMax float64) float64 {
return ScaleMinMax(val, stats.Min, stats.Max, outputMin, outputMax)
}
func (stats *FeatureStats) ScaleStddev(val float64) float64 {
return ScaleStddev(val, stats.Mean(), stats.Stddev(), stats.Min, stats.Max)
}
func GetMinMax(header *bitflow.Header, samples []*bitflow.Sample) ([]float64, []float64) {
min := make([]float64, len(header.Fields))
max := make([]float64, len(header.Fields))
for num := range header.Fields {
min[num] = math.MaxFloat64
max[num] = -math.MaxFloat64
}
for _, sample := range samples {
for i, val := range sample.Values {
min[i] = math.Min(min[i], float64(val))
max[i] = math.Max(max[i], float64(val))
}
}
return min, max
}
func GetStats(header *bitflow.Header, samples []*bitflow.Sample) []FeatureStats {
res := make([]FeatureStats, len(header.Fields))
for _, sample := range samples {
for i, val := range sample.Values {
res[i].Push(float64(val))
}
}
return res
}
func ScaleStddev(val float64, mean, stddev, min, max float64) float64 {
res := (val - mean) / stddev
if !IsValidNumber(res) {
// Special case for zero standard deviation: fallback to min-max scaling
res = ScaleMinMax(float64(val), min, max, -1, 1)
}
return res
}
func ScaleMinMax(val, min, max, outputMin, outputMax float64) float64 {
res := (val - min) / (max - min)
if IsValidNumber(res) {
// res is now in 0..1, transpose it within the range outputMin..outputMax
res = res*(outputMax-outputMin) + outputMin
} else {
res = (outputMax + outputMin) / 2 // min == max -> pick the middle
}
return res
}