autotrader/utils.go

258 lines
6.1 KiB
Go

package autotrader
import (
"errors"
"math"
"os/exec"
"runtime"
"golang.org/x/exp/constraints"
)
const float64Tolerance = float64(1e-6)
var ErrNotASignedNumber = errors.New("not a signed number")
// Crossover returns true if the latest a value crosses above the latest b value, but only if it just happened. For example, if a series is [1, 2, 3, 4, 5] and b series is [1, 2, 3, 4, 3], then Crossover(a, b) returns false because the latest a value is 5 and the latest b value is 3. However, if a series is [1, 2, 3, 4, 5] and b series is [1, 2, 3, 4, 6], then Crossover(a, b) returns true because the latest a value is 5 and the latest b value is 6
func Crossover(a, b *Series) bool {
return a.Float(-1) > b.Float(-1) && a.Float(-2) <= b.Float(-2)
}
// CrossoverIndex is similar to Crossover, except that it works for IndexedSeries.
func CrossoverIndex[I Index](index I, a, b *IndexedSeries[I]) bool {
aRow, bRow := a.Row(index), b.Row(index)
if aRow < 1 || bRow < 1 {
return false
}
return a.Float(aRow) > b.Float(bRow) && a.Float(aRow-1) <= b.Float(bRow-1)
}
// EasyIndex returns an index to the `n` -length object that allows for negative indexing. For example, EasyIndex(-1, 5) returns 4. This is similar to Python's negative indexing. The return value may be less than zero if (-i) > n.
func EasyIndex(i, n int) int {
if i < 0 {
return n + i
}
return i
}
// EqualApprox returns true if a and b are approximately equal. NaN and Inf are handled correctly. The tolerance is 1e-6 or 0.0000001.
func EqualApprox(a, b float64) bool {
if math.IsNaN(a) || math.IsNaN(b) {
return math.IsNaN(a) && math.IsNaN(b)
} else if math.IsInf(a, 1) || math.IsInf(b, 1) {
return math.IsInf(a, 1) && math.IsInf(b, 1)
} else if math.IsInf(a, -1) || math.IsInf(b, -1) {
return math.IsInf(a, -1) && math.IsInf(b, -1)
}
return math.Abs(a-b) <= float64Tolerance
}
// Round returns f rounded to d decimal places. d may be negative to round to the left of the decimal point.
//
// Examples:
//
// Round(123.456, 0) // 123.0
// Round(123.456, 1) // 123.5
// Round(123.456, -1) // 120.0
func Round(f float64, d int) float64 {
ratio := math.Pow10(d)
return math.Round(f*ratio) / ratio
}
func Abs[T constraints.Integer | constraints.Float](a T) T {
if a < T(0) {
return -a
}
return a
}
func Min[T constraints.Ordered](a, b T) T {
if a < b {
return a
}
return b
}
func Max[T constraints.Ordered](a, b T) T {
if a > b {
return a
}
return b
}
func LeverageToMargin(leverage float64) float64 {
return 1 / leverage
}
func MarginToLeverage(margin float64) float64 {
return 1 / margin
}
// Open opens the specified URL in the default browser of the user.
func Open(url string) error {
var cmd string
var args []string
switch runtime.GOOS {
case "windows":
cmd = "cmd"
args = []string{"/c", "start"}
case "darwin":
cmd = "open"
default: // "linux", "freebsd", "openbsd", "netbsd"
cmd = "xdg-open"
}
args = append(args, url)
return exec.Command(cmd, args...).Start()
}
// LessAny returns true if a < b. a and b must be signed numbers. If a or b is not a signed number, then the function returns false, and the value that was first identified as not a signed number as the interface{} alias 'any'. The order of checking is a -> b. If a is not a signed number, then a is returned as the offender. Else if b is not a signed number, then b is returned as the offender. Else, nil is returned as the offender.
//
// A signed number is any of the following types:
//
// - float64
// - float32
// - int
// - int64
// - int32
// - int16
// - int8
func LessAny(a, b any) (less bool, offender any) {
switch a := a.(type) {
case float64:
switch b := b.(type) {
case float64:
return a < b, nil
case float32:
return a < float64(b), nil
case int:
return a < float64(b), nil
case int64:
return a < float64(b), nil
case int32:
return a < float64(b), nil
case int16:
return a < float64(b), nil
case int8:
return a < float64(b), nil
default:
return false, b
}
case float32:
switch b := b.(type) {
case float64:
return float64(a) < b, nil
case float32:
return a < b, nil
case int:
return float64(a) < float64(b), nil
case int64:
return float64(a) < float64(b), nil
case int32:
return a < float32(b), nil
case int16:
return a < float32(b), nil
case int8:
return a < float32(b), nil
default:
return false, b
}
case int:
switch b := b.(type) {
case float64:
return float64(a) < b, nil
case float32:
return float64(a) < float64(b), nil
case int:
return a < b, nil
case int64:
return int64(a) < b, nil
case int32:
return a < int(b), nil
case int16:
return a < int(b), nil
case int8:
return a < int(b), nil
default:
return false, b
}
case int64:
switch b := b.(type) {
case float64:
return float64(a) < b, nil
case float32:
return float64(a) < float64(b), nil
case int:
return a < int64(b), nil
case int64:
return a < b, nil
case int32:
return a < int64(b), nil
case int16:
return a < int64(b), nil
case int8:
return a < int64(b), nil
default:
return false, b
}
case int32:
switch b := b.(type) {
case float64:
return float64(a) < b, nil
case float32:
return float32(a) < float32(b), nil
case int:
return int(a) < b, nil
case int64:
return int64(a) < b, nil
case int32:
return a < b, nil
case int16:
return a < int32(b), nil
case int8:
return a < int32(b), nil
default:
return false, b
}
case int16:
switch b := b.(type) {
case float64:
return float64(a) < b, nil
case float32:
return float32(a) < b, nil
case int:
return int(a) < b, nil
case int64:
return int64(a) < b, nil
case int32:
return int32(a) < b, nil
case int16:
return a < b, nil
case int8:
return a < int16(b), nil
default:
return false, b
}
case int8:
switch b := b.(type) {
case float64:
return float64(a) < b, nil
case float32:
return float32(a) < b, nil
case int:
return int(a) < b, nil
case int64:
return int64(a) < b, nil
case int32:
return int32(a) < b, nil
case int16:
return int16(a) < b, nil
case int8:
return a < b, nil
default:
return false, b
}
}
return false, a
}