floats: move floats related functions and add crossover, crossunder funcs

pkg/datatype/floats/funcs.go

@@ -0,0 +1,96 @@
+package floats
+
+import "sort"
+
+func Lower(arr []float64, x float64) []float64 {
+	sort.Float64s(arr)
+
+	var rst []float64
+	for _, a := range arr {
+		// filter prices that are Lower than the current closed price
+		if a > x {
+			continue
+		}
+
+		rst = append(rst, a)
+	}
+
+	return rst
+}
+
+func Higher(arr []float64, x float64) []float64 {
+	sort.Float64s(arr)
+
+	var rst []float64
+	for _, a := range arr {
+		// filter prices that are Lower than the current closed price
+		if a < x {
+			continue
+		}
+		rst = append(rst, a)
+	}
+
+	return rst
+}
+
+func Group(arr []float64, minDistance float64) []float64 {
+	if len(arr) == 0 {
+		return nil
+	}
+
+	var groups []float64
+	var grp = []float64{arr[0]}
+	for _, price := range arr {
+		avg := Average(grp)
+		if (price / avg) > (1.0 + minDistance) {
+			groups = append(groups, avg)
+			grp = []float64{price}
+		} else {
+			grp = append(grp, price)
+		}
+	}
+
+	if len(grp) > 0 {
+		groups = append(groups, Average(grp))
+	}
+
+	return groups
+}
+
+func Average(arr []float64) float64 {
+	s := 0.0
+	for _, a := range arr {
+		s += a
+	}
+	return s / float64(len(arr))
+}
+
+
+// CrossOver returns true if series1 is crossing over series2.
+//
+//    NOTE: Usually this is used with Media Average Series to check if it crosses for buy signals.
+//          It assumes first values are the most recent.
+//          The crossover function does not use most recent value, since usually it's not a complete candle.
+//          The second recent values and the previous are used, instead.
+func CrossOver(series1 []float64, series2 []float64) bool {
+	if len(series1) < 3 || len(series2) < 3 {
+		return false
+	}
+
+	N := len(series1)
+
+	return series1[N-2] <= series2[N-2] && series1[N-1] > series2[N-1]
+}
+
+// CrossUnder returns true if series1 is crossing under series2.
+//
+//    NOTE: Usually this is used with Media Average Series to check if it crosses for sell signals.
+func CrossUnder(series1 []float64, series2 []float64) bool {
+	if len(series1) < 3 || len(series2) < 3 {
+		return false
+	}
+
+	N := len(series1)
+
+	return series1[N-1] <= series2[N-1] && series1[N-2] > series2[N-2]
+}

pkg/strategy/pivotshort/resistance.go

@@ -4,11 +4,11 @@ import (
 	"context"
 
 	"github.com/c9s/bbgo/pkg/bbgo"
+	"github.com/c9s/bbgo/pkg/datatype/floats"
 	"github.com/c9s/bbgo/pkg/fixedpoint"
 	"github.com/c9s/bbgo/pkg/indicator"
 	"github.com/c9s/bbgo/pkg/risk"
 	"github.com/c9s/bbgo/pkg/types"
-	"github.com/c9s/bbgo/pkg/util"
 )
 
 type ResistanceShort struct {
@@ -190,9 +190,9 @@ func (s *ResistanceShort) placeResistanceOrders(ctx context.Context, resistanceP
 }
 
 func findPossibleSupportPrices(closePrice float64, groupDistance float64, lows []float64) []float64 {
-	return util.Group(util.Lower(lows, closePrice), groupDistance)
+	return floats.Group(floats.Lower(lows, closePrice), groupDistance)
 }
 
 func findPossibleResistancePrices(closePrice float64, groupDistance float64, lows []float64) []float64 {
-	return util.Group(util.Higher(lows, closePrice), groupDistance)
+	return floats.Group(floats.Higher(lows, closePrice), groupDistance)
 }

pkg/util/math.go

@@ -2,7 +2,6 @@ package util
 
 import (
 	"math"
-	"sort"
 	"strconv"
 
 	"github.com/c9s/bbgo/pkg/fixedpoint"
@@ -59,65 +58,3 @@ func NotZero(v float64) bool {
 	return math.Abs(v) > epsilon
 }
 
-func Lower(arr []float64, x float64) []float64 {
-	sort.Float64s(arr)
-
-	var rst []float64
-	for _, a := range arr {
-		// filter prices that are Lower than the current closed price
-		if a > x {
-			continue
-		}
-
-		rst = append(rst, a)
-	}
-
-	return rst
-}
-
-func Higher(arr []float64, x float64) []float64 {
-	sort.Float64s(arr)
-
-	var rst []float64
-	for _, a := range arr {
-		// filter prices that are Lower than the current closed price
-		if a < x {
-			continue
-		}
-		rst = append(rst, a)
-	}
-
-	return rst
-}
-
-func Group(arr []float64, minDistance float64) []float64 {
-	if len(arr) == 0 {
-		return nil
-	}
-
-	var groups []float64
-	var grp = []float64{arr[0]}
-	for _, price := range arr {
-		avg := Average(grp)
-		if (price / avg) > (1.0 + minDistance) {
-			groups = append(groups, avg)
-			grp = []float64{price}
-		} else {
-			grp = append(grp, price)
-		}
-	}
-
-	if len(grp) > 0 {
-		groups = append(groups, Average(grp))
-	}
-
-	return groups
-}
-
-func Average(arr []float64) float64 {
-	s := 0.0
-	for _, a := range arr {
-		s += a
-	}
-	return s / float64(len(arr))
-}