package rtree

import "go-hep.org/x/hep/groot/rtree"

Package rtree contains the interfaces and types to decode, read, concatenate and iterate over ROOT Trees.

Example (CreateEventNtupleFullSplit)

Code:play  

package main

import (
	"bytes"
	"fmt"
	"log"
	"reflect"

	"go-hep.org/x/hep/groot"
	"go-hep.org/x/hep/groot/rcmd"
	"go-hep.org/x/hep/groot/rdict"
	"go-hep.org/x/hep/groot/rtree"
)

func main() {
	type P4 struct {
		Px float64 `groot:"px"`
		Py float64 `groot:"py"`
		Pz float64 `groot:"pz"`
		E  float64 `groot:"ene"`
	}

	type Particle struct {
		ID int32 `groot:"id"`
		P4 P4    `groot:"p4"`
	}

	type Event struct {
		I32 int32      `groot:"i32"`
		F64 float64    `groot:"f64"`
		Str string     `groot:"str"`
		Arr [5]float64 `groot:"arr"`
		Sli []float64  `groot:"sli"`
		P4  P4         `groot:"p4"`
		Ps  []Particle `groot:"mc"`
	}

	// register streamers
	for _, typ := range []reflect.Type{
		reflect.TypeOf(P4{}),
		reflect.TypeOf(Particle{}),
		reflect.TypeOf(Event{}),
	} {

		rdict.StreamerInfos.Add(rdict.StreamerOf(
			rdict.StreamerInfos,
			typ,
		))
	}

	const (
		fname = "../testdata/groot-event-ntuple-fullsplit.root"
		nevts = 5
	)

	func() {
		f, err := groot.Create(fname)
		if err != nil {
			log.Fatalf("could not create ROOT file: %+v", err)
		}
		defer f.Close()

		var (
			evt   Event
			wvars = rtree.WriteVarsFromStruct(&evt)
		)

		tree, err := rtree.NewWriter(f, "mytree", wvars)
		if err != nil {
			log.Fatalf("could not create tree writer: %+v", err)
		}
		defer tree.Close()

		fmt.Printf("-- created tree %q:\n", tree.Name())
		for i, b := range tree.Branches() {
			fmt.Printf("branch[%d]: name=%q, title=%q\n", i, b.Name(), b.Title())
		}

		for i := 0; i < nevts; i++ {
			evt.I32 = int32(i)
			evt.F64 = float64(i)
			evt.Str = fmt.Sprintf("evt-%0d", i)
			evt.Arr = [5]float64{float64(i), float64(i + 1), float64(i + 2), float64(i + 3), float64(i + 4)}
			evt.Sli = []float64{float64(i), float64(i + 1), float64(i + 2), float64(i + 3), float64(i + 4)}[:i]
			evt.P4 = P4{Px: float64(i), Py: float64(i + 1), Pz: float64(i + 2), E: float64(i + 3)}
			evt.Ps = []Particle{
				{ID: int32(i), P4: evt.P4},
				{ID: int32(i + 1), P4: evt.P4},
				{ID: int32(i + 2), P4: evt.P4},
				{ID: int32(i + 3), P4: evt.P4},
				{ID: int32(i + 4), P4: evt.P4},
			}[:i]

			_, err = tree.Write()
			if err != nil {
				log.Fatalf("could not write event %d: %+v", i, err)
			}
		}
		fmt.Printf("-- filled tree with %d entries\n", tree.Entries())

		err = tree.Close()
		if err != nil {
			log.Fatalf("could not write tree: %+v", err)
		}

		err = f.Close()
		if err != nil {
			log.Fatalf("could not close tree: %+v", err)
		}
	}()

	{
		fmt.Printf("-- read back ROOT file\n")
		out := new(bytes.Buffer)
		err := rcmd.List(out, fname, rcmd.ListTrees(true))
		if err != nil {
			log.Fatalf("could not list ROOT file content: %+v", err)
		}
		fmt.Printf("%s\n", out.String())
	}

	{
		var (
			deep   = true
			filter = func(name string) bool { return true }
		)
		out := new(bytes.Buffer)
		err := rcmd.Dump(out, fname, deep, filter)
		if err != nil {
			log.Fatalf("could not dump ROOT file: %+v", err)
		}
		fmt.Printf("%s\n", out.String())
	}

}

Output:

-- created tree "mytree":
branch[0]: name="i32", title="i32/I"
branch[1]: name="f64", title="f64/D"
branch[2]: name="str", title="str/C"
branch[3]: name="arr", title="arr[5]/D"
branch[4]: name="sli", title="sli"
branch[5]: name="p4", title="p4"
branch[6]: name="mc", title="mc"
-- filled tree with 5 entries
-- read back ROOT file
=== [../testdata/groot-event-ntuple-fullsplit.root] ===
version: 63200
  TTree mytree             (entries=5)
    i32 "i32/I"    TBranch
    f64 "f64/D"    TBranch
    str "str/C"    TBranch
    arr "arr[5]/D" TBranch
    sli "sli"      TBranchElement
    p4  "p4"       TBranchElement
    mc  "mc"       TBranchElement

key[000]: mytree;1 "" (TTree)
[000][i32]: 0
[000][f64]: 0
[000][str]: evt-0
[000][arr]: [0 1 2 3 4]
[000][sli]: []
[000][p4]: {0 1 2 3}
[000][mc]: []
[001][i32]: 1
[001][f64]: 1
[001][str]: evt-1
[001][arr]: [1 2 3 4 5]
[001][sli]: [1]
[001][p4]: {1 2 3 4}
[001][mc]: [{1 {1 2 3 4}}]
[002][i32]: 2
[002][f64]: 2
[002][str]: evt-2
[002][arr]: [2 3 4 5 6]
[002][sli]: [2 3]
[002][p4]: {2 3 4 5}
[002][mc]: [{2 {2 3 4 5}} {3 {2 3 4 5}}]
[003][i32]: 3
[003][f64]: 3
[003][str]: evt-3
[003][arr]: [3 4 5 6 7]
[003][sli]: [3 4 5]
[003][p4]: {3 4 5 6}
[003][mc]: [{3 {3 4 5 6}} {4 {3 4 5 6}} {5 {3 4 5 6}}]
[004][i32]: 4
[004][f64]: 4
[004][str]: evt-4
[004][arr]: [4 5 6 7 8]
[004][sli]: [4 5 6 7]
[004][p4]: {4 5 6 7}
[004][mc]: [{4 {4 5 6 7}} {5 {4 5 6 7}} {6 {4 5 6 7}} {7 {4 5 6 7}}]
Example (CreateEventNtupleNoSplit)

Code:play  

package main

import (
	"bytes"
	"fmt"
	"log"
	"reflect"

	"go-hep.org/x/hep/groot"
	"go-hep.org/x/hep/groot/rcmd"
	"go-hep.org/x/hep/groot/rdict"
	"go-hep.org/x/hep/groot/rtree"
)

func main() {
	type P4 struct {
		Px float64 `groot:"px"`
		Py float64 `groot:"py"`
		Pz float64 `groot:"pz"`
		E  float64 `groot:"ene"`
	}

	type Particle struct {
		ID int32 `groot:"id"`
		P4 P4    `groot:"p4"`
	}

	type Event struct {
		I32 int32      `groot:"i32"`
		F64 float64    `groot:"f64"`
		Str string     `groot:"str"`
		Arr [5]float64 `groot:"arr"`
		Sli []float64  `groot:"sli"`
		P4  P4         `groot:"p4"`
		Ps  []Particle `groot:"mc"`
	}

	// register streamers
	for _, typ := range []reflect.Type{
		reflect.TypeOf(P4{}),
		reflect.TypeOf(Particle{}),
		reflect.TypeOf(Event{}),
	} {

		rdict.StreamerInfos.Add(rdict.StreamerOf(
			rdict.StreamerInfos,
			typ,
		))
	}

	const (
		fname = "../testdata/groot-event-ntuple-nosplit.root"
		nevts = 5
	)

	func() {
		f, err := groot.Create(fname)
		if err != nil {
			log.Fatalf("could not create ROOT file: %+v", err)
		}
		defer f.Close()

		var (
			evt   Event
			wvars = []rtree.WriteVar{
				{Name: "evt", Value: &evt},
			}
		)

		tree, err := rtree.NewWriter(f, "mytree", wvars)
		if err != nil {
			log.Fatalf("could not create tree writer: %+v", err)
		}
		defer tree.Close()

		fmt.Printf("-- created tree %q:\n", tree.Name())
		for i, b := range tree.Branches() {
			fmt.Printf("branch[%d]: name=%q, title=%q\n", i, b.Name(), b.Title())
		}

		for i := 0; i < nevts; i++ {
			evt.I32 = int32(i)
			evt.F64 = float64(i)
			evt.Str = fmt.Sprintf("evt-%0d", i)
			evt.Arr = [5]float64{float64(i), float64(i + 1), float64(i + 2), float64(i + 3), float64(i + 4)}
			evt.Sli = []float64{float64(i), float64(i + 1), float64(i + 2), float64(i + 3), float64(i + 4)}[:i]
			evt.P4 = P4{Px: float64(i), Py: float64(i + 1), Pz: float64(i + 2), E: float64(i + 3)}
			evt.Ps = []Particle{
				{ID: int32(i), P4: evt.P4},
				{ID: int32(i + 1), P4: evt.P4},
				{ID: int32(i + 2), P4: evt.P4},
				{ID: int32(i + 3), P4: evt.P4},
				{ID: int32(i + 4), P4: evt.P4},
			}[:i]

			_, err = tree.Write()
			if err != nil {
				log.Fatalf("could not write event %d: %+v", i, err)
			}
		}
		fmt.Printf("-- filled tree with %d entries\n", tree.Entries())

		err = tree.Close()
		if err != nil {
			log.Fatalf("could not write tree: %+v", err)
		}

		err = f.Close()
		if err != nil {
			log.Fatalf("could not close tree: %+v", err)
		}
	}()

	{
		fmt.Printf("-- read back ROOT file\n")
		out := new(bytes.Buffer)
		err := rcmd.List(out, fname, rcmd.ListTrees(true))
		if err != nil {
			log.Fatalf("could not list ROOT file content: %+v", err)
		}
		fmt.Printf("%s\n", out.String())
	}

	{
		var (
			deep   = true
			filter = func(name string) bool { return true }
		)
		out := new(bytes.Buffer)
		err := rcmd.Dump(out, fname, deep, filter)
		if err != nil {
			log.Fatalf("could not dump ROOT file: %+v", err)
		}
		fmt.Printf("%s\n", out.String())
	}

}

Output:

-- created tree "mytree":
branch[0]: name="evt", title="evt"
-- filled tree with 5 entries
-- read back ROOT file
=== [../testdata/groot-event-ntuple-nosplit.root] ===
version: 63200
  TTree mytree          (entries=5)
    evt "evt"   TBranchElement

key[000]: mytree;1 "" (TTree)
[000][evt]: {0 0 evt-0 [0 1 2 3 4] [] {0 1 2 3} []}
[001][evt]: {1 1 evt-1 [1 2 3 4 5] [1] {1 2 3 4} [{1 {1 2 3 4}}]}
[002][evt]: {2 2 evt-2 [2 3 4 5 6] [2 3] {2 3 4 5} [{2 {2 3 4 5}} {3 {2 3 4 5}}]}
[003][evt]: {3 3 evt-3 [3 4 5 6 7] [3 4 5] {3 4 5 6} [{3 {3 4 5 6}} {4 {3 4 5 6}} {5 {3 4 5 6}}]}
[004][evt]: {4 4 evt-4 [4 5 6 7 8] [4 5 6 7] {4 5 6 7} [{4 {4 5 6 7}} {5 {4 5 6 7}} {6 {4 5 6 7}} {7 {4 5 6 7}}]}
Example (CreateFlatNtuple)

Code:play  

package main

import (
	"fmt"
	"log"

	"go-hep.org/x/hep/groot"
	"go-hep.org/x/hep/groot/rtree"
)

func main() {
	type Data struct {
		I32    int32
		F64    float64
		Str    string
		ArrF64 [5]float64
		N      int32
		SliF64 []float64
	}
	const (
		fname = "../testdata/groot-flat-ntuple.root"
		nevts = 5
	)
	func() {
		f, err := groot.Create(fname)
		if err != nil {
			log.Fatalf("%+v", err)
		}
		defer f.Close()

		var evt Data

		wvars := []rtree.WriteVar{
			{Name: "I32", Value: &evt.I32},
			{Name: "F64", Value: &evt.F64},
			{Name: "Str", Value: &evt.Str},
			{Name: "ArrF64", Value: &evt.ArrF64},
			{Name: "N", Value: &evt.N},
			{Name: "SliF64", Value: &evt.SliF64, Count: "N"},
		}
		tree, err := rtree.NewWriter(f, "mytree", wvars)
		if err != nil {
			log.Fatalf("could not create tree writer: %+v", err)
		}
		defer tree.Close()

		fmt.Printf("-- created tree %q:\n", tree.Name())
		for i, b := range tree.Branches() {
			fmt.Printf("branch[%d]: name=%q, title=%q\n", i, b.Name(), b.Title())
		}

		for i := 0; i < nevts; i++ {
			evt.I32 = int32(i)
			evt.F64 = float64(i)
			evt.Str = fmt.Sprintf("evt-%0d", i)
			evt.ArrF64 = [5]float64{float64(i), float64(i + 1), float64(i + 2), float64(i + 3), float64(i + 4)}
			evt.N = int32(i)
			evt.SliF64 = []float64{float64(i), float64(i + 1), float64(i + 2), float64(i + 3), float64(i + 4)}[:i]
			_, err = tree.Write()
			if err != nil {
				log.Fatalf("could not write event %d: %+v", i, err)
			}
		}
		fmt.Printf("-- filled tree with %d entries\n", tree.Entries())

		err = tree.Close()
		if err != nil {
			log.Fatalf("could not write tree: %+v", err)
		}

		err = f.Close()
		if err != nil {
			log.Fatalf("could not close tree: %+v", err)
		}
	}()

	func() {
		fmt.Printf("-- read back ROOT file\n")
		f, err := groot.Open(fname)
		if err != nil {
			log.Fatalf("could not open ROOT file: %+v", err)
		}
		defer f.Close()

		obj, err := f.Get("mytree")
		if err != nil {
			log.Fatalf("%+v", err)
		}

		tree := obj.(rtree.Tree)

		var data Data
		r, err := rtree.NewReader(tree, rtree.ReadVarsFromStruct(&data))
		if err != nil {
			log.Fatal(err)
		}
		defer r.Close()

		err = r.Read(func(ctx rtree.RCtx) error {
			fmt.Printf("entry[%d]: %+v\n", ctx.Entry, data)
			return nil
		})

		if err != nil {
			log.Fatal(err)
		}
	}()

}

Output:

-- created tree "mytree":
branch[0]: name="I32", title="I32/I"
branch[1]: name="F64", title="F64/D"
branch[2]: name="Str", title="Str/C"
branch[3]: name="ArrF64", title="ArrF64[5]/D"
branch[4]: name="N", title="N/I"
branch[5]: name="SliF64", title="SliF64[N]/D"
-- filled tree with 5 entries
-- read back ROOT file
entry[0]: {I32:0 F64:0 Str:evt-0 ArrF64:[0 1 2 3 4] N:0 SliF64:[]}
entry[1]: {I32:1 F64:1 Str:evt-1 ArrF64:[1 2 3 4 5] N:1 SliF64:[1]}
entry[2]: {I32:2 F64:2 Str:evt-2 ArrF64:[2 3 4 5 6] N:2 SliF64:[2 3]}
entry[3]: {I32:3 F64:3 Str:evt-3 ArrF64:[3 4 5 6 7] N:3 SliF64:[3 4 5]}
entry[4]: {I32:4 F64:4 Str:evt-4 ArrF64:[4 5 6 7 8] N:4 SliF64:[4 5 6 7]}
Example (CreateFlatNtupleFromStruct)

Code:play  

package main

import (
	"fmt"
	"log"

	"go-hep.org/x/hep/groot"
	"go-hep.org/x/hep/groot/rtree"
)

func main() {
	type Data struct {
		I32    int32
		F64    float64
		Str    string
		ArrF64 [5]float64
		N      int32
		SliF64 []float64 `groot:"SliF64[N]"`
	}
	const (
		fname = "../testdata/groot-flat-ntuple-with-struct.root"
		nevts = 5
	)
	func() {
		f, err := groot.Create(fname)
		if err != nil {
			log.Fatalf("%+v", err)
		}
		defer f.Close()

		var evt Data

		tree, err := rtree.NewWriter(f, "mytree", rtree.WriteVarsFromStruct(&evt))
		if err != nil {
			log.Fatalf("could not create tree writer: %+v", err)
		}
		defer tree.Close()

		fmt.Printf("-- created tree %q:\n", tree.Name())
		for i, b := range tree.Branches() {
			fmt.Printf("branch[%d]: name=%q, title=%q\n", i, b.Name(), b.Title())
		}

		for i := 0; i < nevts; i++ {
			evt.I32 = int32(i)
			evt.F64 = float64(i)
			evt.Str = fmt.Sprintf("evt-%0d", i)
			evt.ArrF64 = [5]float64{float64(i), float64(i + 1), float64(i + 2), float64(i + 3), float64(i + 4)}
			evt.N = int32(i)
			evt.SliF64 = []float64{float64(i), float64(i + 1), float64(i + 2), float64(i + 3), float64(i + 4)}[:i]
			_, err = tree.Write()
			if err != nil {
				log.Fatalf("could not write event %d: %+v", i, err)
			}
		}
		fmt.Printf("-- filled tree with %d entries\n", tree.Entries())

		err = tree.Close()
		if err != nil {
			log.Fatalf("could not write tree: %+v", err)
		}

		err = f.Close()
		if err != nil {
			log.Fatalf("could not close tree: %+v", err)
		}
	}()

	func() {
		fmt.Printf("-- read back ROOT file\n")
		f, err := groot.Open(fname)
		if err != nil {
			log.Fatalf("could not open ROOT file: %+v", err)
		}
		defer f.Close()

		obj, err := f.Get("mytree")
		if err != nil {
			log.Fatalf("%+v", err)
		}

		tree := obj.(rtree.Tree)

		var data Data
		r, err := rtree.NewReader(tree, rtree.ReadVarsFromStruct(&data))
		if err != nil {
			log.Fatal(err)
		}
		defer r.Close()

		err = r.Read(func(ctx rtree.RCtx) error {
			fmt.Printf("entry[%d]: %+v\n", ctx.Entry, data)
			return nil
		})

		if err != nil {
			log.Fatal(err)
		}
	}()

}

Output:

-- created tree "mytree":
branch[0]: name="I32", title="I32/I"
branch[1]: name="F64", title="F64/D"
branch[2]: name="Str", title="Str/C"
branch[3]: name="ArrF64", title="ArrF64[5]/D"
branch[4]: name="N", title="N/I"
branch[5]: name="SliF64", title="SliF64[N]/D"
-- filled tree with 5 entries
-- read back ROOT file
entry[0]: {I32:0 F64:0 Str:evt-0 ArrF64:[0 1 2 3 4] N:0 SliF64:[]}
entry[1]: {I32:1 F64:1 Str:evt-1 ArrF64:[1 2 3 4 5] N:1 SliF64:[1]}
entry[2]: {I32:2 F64:2 Str:evt-2 ArrF64:[2 3 4 5 6] N:2 SliF64:[2 3]}
entry[3]: {I32:3 F64:3 Str:evt-3 ArrF64:[3 4 5 6 7] N:3 SliF64:[3 4 5]}
entry[4]: {I32:4 F64:4 Str:evt-4 ArrF64:[4 5 6 7 8] N:4 SliF64:[4 5 6 7]}
Example (CreateFlatNtupleWithLZMA)

Code:play  

package main

import (
	"compress/flate"
	"fmt"
	"log"

	"go-hep.org/x/hep/groot"
	"go-hep.org/x/hep/groot/rtree"
)

func main() {
	type Data struct {
		I32    int32
		F64    float64
		Str    string
		ArrF64 [5]float64
		N      int32
		SliF64 []float64
	}
	const (
		fname = "../testdata/groot-flat-ntuple-with-lzma.root"
		nevts = 5
	)
	func() {
		f, err := groot.Create(fname)
		if err != nil {
			log.Fatalf("%+v", err)
		}
		defer f.Close()

		var evt Data

		wvars := []rtree.WriteVar{
			{Name: "I32", Value: &evt.I32},
			{Name: "F64", Value: &evt.F64},
			{Name: "Str", Value: &evt.Str},
			{Name: "ArrF64", Value: &evt.ArrF64},
			{Name: "N", Value: &evt.N},
			{Name: "SliF64", Value: &evt.SliF64, Count: "N"},
		}
		tree, err := rtree.NewWriter(f, "mytree", wvars, rtree.WithLZMA(flate.BestCompression), rtree.WithBasketSize(32*1024))
		if err != nil {
			log.Fatalf("could not create tree writer: %+v", err)
		}
		defer tree.Close()

		fmt.Printf("-- created tree %q:\n", tree.Name())
		for i, b := range tree.Branches() {
			fmt.Printf("branch[%d]: name=%q, title=%q\n", i, b.Name(), b.Title())
		}

		for i := 0; i < nevts; i++ {
			evt.I32 = int32(i)
			evt.F64 = float64(i)
			evt.Str = fmt.Sprintf("evt-%0d", i)
			evt.ArrF64 = [5]float64{float64(i), float64(i + 1), float64(i + 2), float64(i + 3), float64(i + 4)}
			evt.N = int32(i)
			evt.SliF64 = []float64{float64(i), float64(i + 1), float64(i + 2), float64(i + 3), float64(i + 4)}[:i]
			_, err = tree.Write()
			if err != nil {
				log.Fatalf("could not write event %d: %+v", i, err)
			}
		}
		fmt.Printf("-- filled tree with %d entries\n", tree.Entries())

		err = tree.Close()
		if err != nil {
			log.Fatalf("could not write tree: %+v", err)
		}

		err = f.Close()
		if err != nil {
			log.Fatalf("could not close tree: %+v", err)
		}
	}()

	func() {
		fmt.Printf("-- read back ROOT file\n")
		f, err := groot.Open(fname)
		if err != nil {
			log.Fatalf("could not open ROOT file: %+v", err)
		}
		defer f.Close()

		obj, err := f.Get("mytree")
		if err != nil {
			log.Fatalf("%+v", err)
		}

		tree := obj.(rtree.Tree)

		var data Data
		r, err := rtree.NewReader(tree, rtree.ReadVarsFromStruct(&data))
		if err != nil {
			log.Fatal(err)
		}
		defer r.Close()

		err = r.Read(func(ctx rtree.RCtx) error {
			fmt.Printf("entry[%d]: %+v\n", ctx.Entry, data)
			return nil
		})

		if err != nil {
			log.Fatal(err)
		}
	}()

}

Output:

-- created tree "mytree":
branch[0]: name="I32", title="I32/I"
branch[1]: name="F64", title="F64/D"
branch[2]: name="Str", title="Str/C"
branch[3]: name="ArrF64", title="ArrF64[5]/D"
branch[4]: name="N", title="N/I"
branch[5]: name="SliF64", title="SliF64[N]/D"
-- filled tree with 5 entries
-- read back ROOT file
entry[0]: {I32:0 F64:0 Str:evt-0 ArrF64:[0 1 2 3 4] N:0 SliF64:[]}
entry[1]: {I32:1 F64:1 Str:evt-1 ArrF64:[1 2 3 4 5] N:1 SliF64:[1]}
entry[2]: {I32:2 F64:2 Str:evt-2 ArrF64:[2 3 4 5 6] N:2 SliF64:[2 3]}
entry[3]: {I32:3 F64:3 Str:evt-3 ArrF64:[3 4 5 6 7] N:3 SliF64:[3 4 5]}
entry[4]: {I32:4 F64:4 Str:evt-4 ArrF64:[4 5 6 7 8] N:4 SliF64:[4 5 6 7]}

Index

Examples

Functions

func Copy 

func Copy(dst Writer, src *Reader) (int64, error)

Copy copies from src to dst until either the reader is depleted or an error occurs. It returns the number of bytes copied and the first error encountered while copying, if any.

func FileOf 

func FileOf(tree Tree) *riofs.File

FileOf returns the file hosting the given Tree. If the tree is not connected to any ROOT file, nil is returned.

Types

type Basket 

type Basket struct {
	// contains filtered or unexported fields
}

func (*Basket) Class 

func (b *Basket) Class() string

func (*Basket) MarshalROOT 

func (b *Basket) MarshalROOT(w *rbytes.WBuffer) (int, error)

func (*Basket) Name 

func (b *Basket) Name() string

func (*Basket) RVersion 

func (*Basket) RVersion() int16

func (*Basket) Title 

func (b *Basket) Title() string

func (*Basket) UnmarshalROOT 

func (b *Basket) UnmarshalROOT(r *rbytes.RBuffer) error

type Branch 

type Branch interface {
	root.Named

	Branches() []Branch
	Leaves() []Leaf
	Branch(name string) Branch
	Leaf(name string) Leaf

	GoType() reflect.Type
	// contains filtered or unexported methods
}

Branch describes a branch of a ROOT Tree.

type Leaf 

type Leaf interface {
	root.Named

	Branch() Branch
	HasRange() bool
	IsUnsigned() bool
	LeafCount() Leaf // returns the leaf count if is variable length
	Len() int        // Len returns the number of fixed length elements
	LenType() int    // LenType returns the number of bytes for this data type
	Shape() []int
	Offset() int
	Kind() reflect.Kind
	Type() reflect.Type
	TypeName() string
	// contains filtered or unexported methods
}

Leaf describes branches data types

type LeafB 

type LeafB struct {
	// contains filtered or unexported fields
}

LeafB implements ROOT TLeafB

func (*LeafB) Branch 

func (leaf *LeafB) Branch() Branch

func (*LeafB) Class 

func (leaf *LeafB) Class() string

Class returns the ROOT class name.

func (*LeafB) HasRange 

func (leaf *LeafB) HasRange() bool

func (*LeafB) IsUnsigned 

func (leaf *LeafB) IsUnsigned() bool

func (*LeafB) Kind 

func (leaf *LeafB) Kind() reflect.Kind

Kind returns the leaf's kind.

func (*LeafB) LeafCount 

func (leaf *LeafB) LeafCount() Leaf

func (*LeafB) Len 

func (leaf *LeafB) Len() int

func (*LeafB) LenType 

func (leaf *LeafB) LenType() int

func (*LeafB) MarshalROOT 

func (leaf *LeafB) MarshalROOT(w *rbytes.WBuffer) (int, error)

func (*LeafB) Maximum 

func (leaf *LeafB) Maximum() int8

Maximum returns the maximum value of the leaf.

func (*LeafB) Minimum 

func (leaf *LeafB) Minimum() int8

Minimum returns the minimum value of the leaf.

func (*LeafB) Name 

func (leaf *LeafB) Name() string

Name returns the name of the instance

func (*LeafB) Offset 

func (leaf *LeafB) Offset() int

func (*LeafB) RVersion 

func (*LeafB) RVersion() int16

func (*LeafB) Shape 

func (leaf *LeafB) Shape() []int

func (*LeafB) Title 

func (leaf *LeafB) Title() string

Title returns the title of the instance

func (*LeafB) Type 

func (leaf *LeafB) Type() reflect.Type

Type returns the leaf's type.

func (*LeafB) TypeName 

func (leaf *LeafB) TypeName() string

func (*LeafB) UnmarshalROOT 

func (leaf *LeafB) UnmarshalROOT(r *rbytes.RBuffer) error

type LeafC 

type LeafC struct {
	// contains filtered or unexported fields
}

LeafC implements ROOT TLeafC

func (*LeafC) Branch 

func (leaf *LeafC) Branch() Branch

func (*LeafC) Class 

func (leaf *LeafC) Class() string

Class returns the ROOT class name.

func (*LeafC) HasRange 

func (leaf *LeafC) HasRange() bool

func (*LeafC) IsUnsigned 

func (leaf *LeafC) IsUnsigned() bool

func (*LeafC) Kind 

func (leaf *LeafC) Kind() reflect.Kind

Kind returns the leaf's kind.

func (*LeafC) LeafCount 

func (leaf *LeafC) LeafCount() Leaf

func (*LeafC) Len 

func (leaf *LeafC) Len() int

func (*LeafC) LenType 

func (leaf *LeafC) LenType() int

func (*LeafC) MarshalROOT 

func (leaf *LeafC) MarshalROOT(w *rbytes.WBuffer) (int, error)

func (*LeafC) Maximum 

func (leaf *LeafC) Maximum() int32

Maximum returns the maximum value of the leaf.

func (*LeafC) Minimum 

func (leaf *LeafC) Minimum() int32

Minimum returns the minimum value of the leaf.

func (*LeafC) Name 

func (leaf *LeafC) Name() string

Name returns the name of the instance

func (*LeafC) Offset 

func (leaf *LeafC) Offset() int

func (*LeafC) RVersion 

func (*LeafC) RVersion() int16

func (*LeafC) Shape 

func (leaf *LeafC) Shape() []int

func (*LeafC) Title 

func (leaf *LeafC) Title() string

Title returns the title of the instance

func (*LeafC) Type 

func (leaf *LeafC) Type() reflect.Type

Type returns the leaf's type.

func (*LeafC) TypeName 

func (leaf *LeafC) TypeName() string

func (*LeafC) UnmarshalROOT 

func (leaf *LeafC) UnmarshalROOT(r *rbytes.RBuffer) error

type LeafD 

type LeafD struct {
	// contains filtered or unexported fields
}

LeafD implements ROOT TLeafD

func (*LeafD) Branch 

func (leaf *LeafD) Branch() Branch

func (*LeafD) Class 

func (leaf *LeafD) Class() string

Class returns the ROOT class name.

func (*LeafD) HasRange 

func (leaf *LeafD) HasRange() bool

func (*LeafD) IsUnsigned 

func (leaf *LeafD) IsUnsigned() bool

func (*LeafD) Kind 

func (leaf *LeafD) Kind() reflect.Kind

Kind returns the leaf's kind.

func (*LeafD) LeafCount 

func (leaf *LeafD) LeafCount() Leaf

func (*LeafD) Len 

func (leaf *LeafD) Len() int

func (*LeafD) LenType 

func (leaf *LeafD) LenType() int

func (*LeafD) MarshalROOT 

func (leaf *LeafD) MarshalROOT(w *rbytes.WBuffer) (int, error)

func (*LeafD) Maximum 

func (leaf *LeafD) Maximum() float64

Maximum returns the maximum value of the leaf.

func (*LeafD) Minimum 

func (leaf *LeafD) Minimum() float64

Minimum returns the minimum value of the leaf.

func (*LeafD) Name 

func (leaf *LeafD) Name() string

Name returns the name of the instance

func (*LeafD) Offset 

func (leaf *LeafD) Offset() int

func (*LeafD) RVersion 

func (*LeafD) RVersion() int16

func (*LeafD) Shape 

func (leaf *LeafD) Shape() []int

func (*LeafD) Title 

func (leaf *LeafD) Title() string

Title returns the title of the instance

func (*LeafD) Type 

func (leaf *LeafD) Type() reflect.Type

Type returns the leaf's type.

func (*LeafD) TypeName 

func (leaf *LeafD) TypeName() string

func (*LeafD) UnmarshalROOT 

func (leaf *LeafD) UnmarshalROOT(r *rbytes.RBuffer) error

type LeafD32 

type LeafD32 struct {
	// contains filtered or unexported fields
}

LeafD32 implements ROOT TLeafD32

func (*LeafD32) Branch 

func (leaf *LeafD32) Branch() Branch

func (*LeafD32) Class 

func (leaf *LeafD32) Class() string

Class returns the ROOT class name.

func (*LeafD32) HasRange 

func (leaf *LeafD32) HasRange() bool

func (*LeafD32) IsUnsigned 

func (leaf *LeafD32) IsUnsigned() bool

func (*LeafD32) Kind 

func (leaf *LeafD32) Kind() reflect.Kind

Kind returns the leaf's kind.

func (*LeafD32) LeafCount 

func (leaf *LeafD32) LeafCount() Leaf

func (*LeafD32) Len 

func (leaf *LeafD32) Len() int

func (*LeafD32) LenType 

func (leaf *LeafD32) LenType() int

func (*LeafD32) MarshalROOT 

func (leaf *LeafD32) MarshalROOT(w *rbytes.WBuffer) (int, error)

func (*LeafD32) Maximum 

func (leaf *LeafD32) Maximum() root.Double32

Maximum returns the maximum value of the leaf.

func (*LeafD32) Minimum 

func (leaf *LeafD32) Minimum() root.Double32

Minimum returns the minimum value of the leaf.

func (*LeafD32) Name 

func (leaf *LeafD32) Name() string

Name returns the name of the instance

func (*LeafD32) Offset 

func (leaf *LeafD32) Offset() int

func (*LeafD32) RVersion 

func (*LeafD32) RVersion() int16

func (*LeafD32) Shape 

func (leaf *LeafD32) Shape() []int

func (*LeafD32) Title 

func (leaf *LeafD32) Title() string

Title returns the title of the instance

func (*LeafD32) Type 

func (leaf *LeafD32) Type() reflect.Type

Type returns the leaf's type.

func (*LeafD32) TypeName 

func (leaf *LeafD32) TypeName() string

func (*LeafD32) UnmarshalROOT 

func (leaf *LeafD32) UnmarshalROOT(r *rbytes.RBuffer) error

type LeafF 

type LeafF struct {
	// contains filtered or unexported fields
}

LeafF implements ROOT TLeafF

func (*LeafF) Branch 

func (leaf *LeafF) Branch() Branch

func (*LeafF) Class 

func (leaf *LeafF) Class() string

Class returns the ROOT class name.

func (*LeafF) HasRange 

func (leaf *LeafF) HasRange() bool

func (*LeafF) IsUnsigned 

func (leaf *LeafF) IsUnsigned() bool

func (*LeafF) Kind 

func (leaf *LeafF) Kind() reflect.Kind

Kind returns the leaf's kind.

func (*LeafF) LeafCount 

func (leaf *LeafF) LeafCount() Leaf

func (*LeafF) Len 

func (leaf *LeafF) Len() int

func (*LeafF) LenType 

func (leaf *LeafF) LenType() int

func (*LeafF) MarshalROOT 

func (leaf *LeafF) MarshalROOT(w *rbytes.WBuffer) (int, error)

func (*LeafF) Maximum 

func (leaf *LeafF) Maximum() float32

Maximum returns the maximum value of the leaf.

func (*LeafF) Minimum 

func (leaf *LeafF) Minimum() float32

Minimum returns the minimum value of the leaf.

func (*LeafF) Name 

func (leaf *LeafF) Name() string

Name returns the name of the instance

func (*LeafF) Offset 

func (leaf *LeafF) Offset() int

func (*LeafF) RVersion 

func (*LeafF) RVersion() int16

func (*LeafF) Shape 

func (leaf *LeafF) Shape() []int

func (*LeafF) Title 

func (leaf *LeafF) Title() string

Title returns the title of the instance

func (*LeafF) Type 

func (leaf *LeafF) Type() reflect.Type

Type returns the leaf's type.

func (*LeafF) TypeName 

func (leaf *LeafF) TypeName() string

func (*LeafF) UnmarshalROOT 

func (leaf *LeafF) UnmarshalROOT(r *rbytes.RBuffer) error

type LeafF16 

type LeafF16 struct {
	// contains filtered or unexported fields
}

LeafF16 implements ROOT TLeafF16

func (*LeafF16) Branch 

func (leaf *LeafF16) Branch() Branch

func (*LeafF16) Class 

func (leaf *LeafF16) Class() string

Class returns the ROOT class name.

func (*LeafF16) HasRange 

func (leaf *LeafF16) HasRange() bool

func (*LeafF16) IsUnsigned 

func (leaf *LeafF16) IsUnsigned() bool

func (*LeafF16) Kind 

func (leaf *LeafF16) Kind() reflect.Kind

Kind returns the leaf's kind.

func (*LeafF16) LeafCount 

func (leaf *LeafF16) LeafCount() Leaf

func (*LeafF16) Len 

func (leaf *LeafF16) Len() int

func (*LeafF16) LenType 

func (leaf *LeafF16) LenType() int

func (*LeafF16) MarshalROOT 

func (leaf *LeafF16) MarshalROOT(w *rbytes.WBuffer) (int, error)

func (*LeafF16) Maximum 

func (leaf *LeafF16) Maximum() root.Float16

Maximum returns the maximum value of the leaf.

func (*LeafF16) Minimum 

func (leaf *LeafF16) Minimum() root.Float16

Minimum returns the minimum value of the leaf.

func (*LeafF16) Name 

func (leaf *LeafF16) Name() string

Name returns the name of the instance

func (*LeafF16) Offset 

func (leaf *LeafF16) Offset() int

func (*LeafF16) RVersion 

func (*LeafF16) RVersion() int16

func (*LeafF16) Shape 

func (leaf *LeafF16) Shape() []int

func (*LeafF16) Title 

func (leaf *LeafF16) Title() string

Title returns the title of the instance

func (*LeafF16) Type 

func (leaf *LeafF16) Type() reflect.Type

Type returns the leaf's type.

func (*LeafF16) TypeName 

func (leaf *LeafF16) TypeName() string

func (*LeafF16) UnmarshalROOT 

func (leaf *LeafF16) UnmarshalROOT(r *rbytes.RBuffer) error

type LeafG 

type LeafG struct {
	// contains filtered or unexported fields
}

LeafG implements ROOT TLeafG

func (*LeafG) Branch 

func (leaf *LeafG) Branch() Branch

func (*LeafG) Class 

func (leaf *LeafG) Class() string

Class returns the ROOT class name.

func (*LeafG) HasRange 

func (leaf *LeafG) HasRange() bool

func (*LeafG) IsUnsigned 

func (leaf *LeafG) IsUnsigned() bool

func (*LeafG) Kind 

func (leaf *LeafG) Kind() reflect.Kind

Kind returns the leaf's kind.

func (*LeafG) LeafCount 

func (leaf *LeafG) LeafCount() Leaf

func (*LeafG) Len 

func (leaf *LeafG) Len() int

func (*LeafG) LenType 

func (leaf *LeafG) LenType() int

func (*LeafG) MarshalROOT 

func (leaf *LeafG) MarshalROOT(w *rbytes.WBuffer) (int, error)

func (*LeafG) Maximum 

func (leaf *LeafG) Maximum() int64

Maximum returns the maximum value of the leaf.

func (*LeafG) Minimum 

func (leaf *LeafG) Minimum() int64

Minimum returns the minimum value of the leaf.

func (*LeafG) Name 

func (leaf *LeafG) Name() string

Name returns the name of the instance

func (*LeafG) Offset 

func (leaf *LeafG) Offset() int

func (*LeafG) RVersion 

func (*LeafG) RVersion() int16

func (*LeafG) Shape 

func (leaf *LeafG) Shape() []int

func (*LeafG) Title 

func (leaf *LeafG) Title() string

Title returns the title of the instance

func (*LeafG) Type 

func (leaf *LeafG) Type() reflect.Type

Type returns the leaf's type.

func (*LeafG) TypeName 

func (leaf *LeafG) TypeName() string

func (*LeafG) UnmarshalROOT 

func (leaf *LeafG) UnmarshalROOT(r *rbytes.RBuffer) error

type LeafI 

type LeafI struct {
	// contains filtered or unexported fields
}

LeafI implements ROOT TLeafI

func (*LeafI) Branch 

func (leaf *LeafI) Branch() Branch

func (*LeafI) Class 

func (leaf *LeafI) Class() string

Class returns the ROOT class name.

func (*LeafI) HasRange 

func (leaf *LeafI) HasRange() bool

func (*LeafI) IsUnsigned 

func (leaf *LeafI) IsUnsigned() bool

func (*LeafI) Kind 

func (leaf *LeafI) Kind() reflect.Kind

Kind returns the leaf's kind.

func (*LeafI) LeafCount 

func (leaf *LeafI) LeafCount() Leaf

func (*LeafI) Len 

func (leaf *LeafI) Len() int

func (*LeafI) LenType 

func (leaf *LeafI) LenType() int

func (*LeafI) MarshalROOT 

func (leaf *LeafI) MarshalROOT(w *rbytes.WBuffer) (int, error)

func (*LeafI) Maximum 

func (leaf *LeafI) Maximum() int32

Maximum returns the maximum value of the leaf.

func (*LeafI) Minimum 

func (leaf *LeafI) Minimum() int32

Minimum returns the minimum value of the leaf.

func (*LeafI) Name 

func (leaf *LeafI) Name() string

Name returns the name of the instance

func (*LeafI) Offset 

func (leaf *LeafI) Offset() int

func (*LeafI) RVersion 

func (*LeafI) RVersion() int16

func (*LeafI) Shape 

func (leaf *LeafI) Shape() []int

func (*LeafI) Title 

func (leaf *LeafI) Title() string

Title returns the title of the instance

func (*LeafI) Type 

func (leaf *LeafI) Type() reflect.Type

Type returns the leaf's type.

func (*LeafI) TypeName 

func (leaf *LeafI) TypeName() string

func (*LeafI) UnmarshalROOT 

func (leaf *LeafI) UnmarshalROOT(r *rbytes.RBuffer) error

type LeafL 

type LeafL struct {
	// contains filtered or unexported fields
}

LeafL implements ROOT TLeafL

func (*LeafL) Branch 

func (leaf *LeafL) Branch() Branch

func (*LeafL) Class 

func (leaf *LeafL) Class() string

Class returns the ROOT class name.

func (*LeafL) HasRange 

func (leaf *LeafL) HasRange() bool

func (*LeafL) IsUnsigned 

func (leaf *LeafL) IsUnsigned() bool

func (*LeafL) Kind 

func (leaf *LeafL) Kind() reflect.Kind

Kind returns the leaf's kind.

func (*LeafL) LeafCount 

func (leaf *LeafL) LeafCount() Leaf

func (*LeafL) Len 

func (leaf *LeafL) Len() int

func (*LeafL) LenType 

func (leaf *LeafL) LenType() int

func (*LeafL) MarshalROOT 

func (leaf *LeafL) MarshalROOT(w *rbytes.WBuffer) (int, error)

func (*LeafL) Maximum 

func (leaf *LeafL) Maximum() int64

Maximum returns the maximum value of the leaf.

func (*LeafL) Minimum 

func (leaf *LeafL) Minimum() int64

Minimum returns the minimum value of the leaf.

func (*LeafL) Name 

func (leaf *LeafL) Name() string

Name returns the name of the instance

func (*LeafL) Offset 

func (leaf *LeafL) Offset() int

func (*LeafL) RVersion 

func (*LeafL) RVersion() int16

func (*LeafL) Shape 

func (leaf *LeafL) Shape() []int

func (*LeafL) Title 

func (leaf *LeafL) Title() string

Title returns the title of the instance

func (*LeafL) Type 

func (leaf *LeafL) Type() reflect.Type

Type returns the leaf's type.

func (*LeafL) TypeName 

func (leaf *LeafL) TypeName() string

func (*LeafL) UnmarshalROOT 

func (leaf *LeafL) UnmarshalROOT(r *rbytes.RBuffer) error

type LeafO 

type LeafO struct {
	// contains filtered or unexported fields
}

LeafO implements ROOT TLeafO

func (*LeafO) Branch 

func (leaf *LeafO) Branch() Branch

func (*LeafO) Class 

func (leaf *LeafO) Class() string

Class returns the ROOT class name.

func (*LeafO) HasRange 

func (leaf *LeafO) HasRange() bool

func (*LeafO) IsUnsigned 

func (leaf *LeafO) IsUnsigned() bool

func (*LeafO) Kind 

func (leaf *LeafO) Kind() reflect.Kind

Kind returns the leaf's kind.

func (*LeafO) LeafCount 

func (leaf *LeafO) LeafCount() Leaf

func (*LeafO) Len 

func (leaf *LeafO) Len() int

func (*LeafO) LenType 

func (leaf *LeafO) LenType() int

func (*LeafO) MarshalROOT 

func (leaf *LeafO) MarshalROOT(w *rbytes.WBuffer) (int, error)

func (*LeafO) Maximum 

func (leaf *LeafO) Maximum() bool

Maximum returns the maximum value of the leaf.

func (*LeafO) Minimum 

func (leaf *LeafO) Minimum() bool

Minimum returns the minimum value of the leaf.

func (*LeafO) Name 

func (leaf *LeafO) Name() string

Name returns the name of the instance

func (*LeafO) Offset 

func (leaf *LeafO) Offset() int

func (*LeafO) RVersion 

func (*LeafO) RVersion() int16

func (*LeafO) Shape 

func (leaf *LeafO) Shape() []int

func (*LeafO) Title 

func (leaf *LeafO) Title() string

Title returns the title of the instance

func (*LeafO) Type 

func (leaf *LeafO) Type() reflect.Type

Type returns the leaf's type.

func (*LeafO) TypeName 

func (leaf *LeafO) TypeName() string

func (*LeafO) UnmarshalROOT 

func (leaf *LeafO) UnmarshalROOT(r *rbytes.RBuffer) error

type LeafS 

type LeafS struct {
	// contains filtered or unexported fields
}

LeafS implements ROOT TLeafS

func (*LeafS) Branch 

func (leaf *LeafS) Branch() Branch

func (*LeafS) Class 

func (leaf *LeafS) Class() string

Class returns the ROOT class name.

func (*LeafS) HasRange 

func (leaf *LeafS) HasRange() bool

func (*LeafS) IsUnsigned 

func (leaf *LeafS) IsUnsigned() bool

func (*LeafS) Kind 

func (leaf *LeafS) Kind() reflect.Kind

Kind returns the leaf's kind.

func (*LeafS) LeafCount 

func (leaf *LeafS) LeafCount() Leaf

func (*LeafS) Len 

func (leaf *LeafS) Len() int

func (*LeafS) LenType 

func (leaf *LeafS) LenType() int

func (*LeafS) MarshalROOT 

func (leaf *LeafS) MarshalROOT(w *rbytes.WBuffer) (int, error)

func (*LeafS) Maximum 

func (leaf *LeafS) Maximum() int16

Maximum returns the maximum value of the leaf.

func (*LeafS) Minimum 

func (leaf *LeafS) Minimum() int16

Minimum returns the minimum value of the leaf.

func (*LeafS) Name 

func (leaf *LeafS) Name() string

Name returns the name of the instance

func (*LeafS) Offset 

func (leaf *LeafS) Offset() int

func (*LeafS) RVersion 

func (*LeafS) RVersion() int16

func (*LeafS) Shape 

func (leaf *LeafS) Shape() []int

func (*LeafS) Title 

func (leaf *LeafS) Title() string

Title returns the title of the instance

func (*LeafS) Type 

func (leaf *LeafS) Type() reflect.Type

Type returns the leaf's type.

func (*LeafS) TypeName 

func (leaf *LeafS) TypeName() string

func (*LeafS) UnmarshalROOT 

func (leaf *LeafS) UnmarshalROOT(r *rbytes.RBuffer) error

type RCtx 

type RCtx struct {
	Entry int64 // Current tree entry.
}

RCtx provides an entry-wise local context to the tree Reader.

type ReadOption 

type ReadOption func(r *Reader) error

ReadOption configures how a ROOT tree should be traversed.

func WithPrefetchBaskets 

func WithPrefetchBaskets(n int) ReadOption

WithPrefetchBaskets specifies the number of baskets to read-ahead, per branch. The default is 2. The number of prefetch baskets is cap'ed by the number of baskets, per branch.

func WithRange 

func WithRange(beg, end int64) ReadOption

WithRange specifies the half-open interval [beg, end) of entries a Tree reader will read through.

type ReadVar 

type ReadVar struct {
	Name  string      // name of the branch to read
	Leaf  string      // name of the leaf to read
	Value interface{} // pointer to the value to fill
	// contains filtered or unexported fields
}

ReadVar describes a variable to be read out of a tree.

func NewReadVars 

func NewReadVars(t Tree) []ReadVar

NewReadVars returns the complete set of ReadVars to read all the data contained in the provided Tree.

func ReadVarsFromStruct 

func ReadVarsFromStruct(ptr interface{}) []ReadVar

ReadVarsFromStruct returns a list of ReadVars bound to the exported fields of the provided pointer to a struct value.

ReadVarsFromStruct panicks if the provided value is not a pointer to a struct value.

func (ReadVar) Deref 

func (rv ReadVar) Deref() interface{}

Deref returns the value pointed at by this read-var.

type Reader 

type Reader struct {
	// contains filtered or unexported fields
}

Reader reads data from a Tree.

Example

Code:play  

package main

import (
	"fmt"
	"log"

	"go-hep.org/x/hep/groot"
	"go-hep.org/x/hep/groot/rtree"
)

func main() {
	f, err := groot.Open("../testdata/simple.root")
	if err != nil {
		log.Fatalf("could not open ROOT file: %+v", err)
	}
	defer f.Close()

	o, err := f.Get("tree")
	if err != nil {
		log.Fatalf("could not retrieve ROOT tree: %+v", err)
	}
	t := o.(rtree.Tree)

	var (
		v1 int32
		v2 float32
		v3 string

		rvars = []rtree.ReadVar{
			{Name: "one", Value: &v1},
			{Name: "two", Value: &v2},
			{Name: "three", Value: &v3},
		}
	)

	r, err := rtree.NewReader(t, rvars)
	if err != nil {
		log.Fatalf("could not create tree reader: %+v", err)
	}
	defer r.Close()

	err = r.Read(func(ctx rtree.RCtx) error {
		fmt.Printf("evt[%d]: %v, %v, %v\n", ctx.Entry, v1, v2, v3)
		return nil
	})
	if err != nil {
		log.Fatalf("could not process tree: %+v", err)
	}

}

Output:

evt[0]: 1, 1.1, uno
evt[1]: 2, 2.2, dos
evt[2]: 3, 3.3, tres
evt[3]: 4, 4.4, quatro
Example (WithChain)

Code:play  

package main

import (
	"fmt"
	"log"

	"go-hep.org/x/hep/groot"
	"go-hep.org/x/hep/groot/rtree"
)

func main() {
	f, err := groot.Open("../testdata/simple.root")
	if err != nil {
		log.Fatalf("could not open ROOT file: %+v", err)
	}
	defer f.Close()

	o, err := f.Get("tree")
	if err != nil {
		log.Fatalf("could not retrieve ROOT tree: %+v", err)
	}
	t := o.(rtree.Tree)

	t = rtree.Chain(t, t, t, t)

	var (
		v1 int32
		v2 float32
		v3 string

		rvars = []rtree.ReadVar{
			{Name: "one", Value: &v1},
			{Name: "two", Value: &v2},
			{Name: "three", Value: &v3},
		}
	)

	r, err := rtree.NewReader(t, rvars,
		rtree.WithRange(0, -1),
		rtree.WithPrefetchBaskets(2),
	)
	if err != nil {
		log.Fatalf("could not create tree reader: %+v", err)
	}
	defer r.Close()

	err = r.Read(func(ctx rtree.RCtx) error {
		fmt.Printf("evt[%d]: %v, %v, %v\n", ctx.Entry, v1, v2, v3)
		return nil
	})
	if err != nil {
		log.Fatalf("could not process tree: %+v", err)
	}

}

Output:

evt[0]: 1, 1.1, uno
evt[1]: 2, 2.2, dos
evt[2]: 3, 3.3, tres
evt[3]: 4, 4.4, quatro
evt[4]: 1, 1.1, uno
evt[5]: 2, 2.2, dos
evt[6]: 3, 3.3, tres
evt[7]: 4, 4.4, quatro
evt[8]: 1, 1.1, uno
evt[9]: 2, 2.2, dos
evt[10]: 3, 3.3, tres
evt[11]: 4, 4.4, quatro
evt[12]: 1, 1.1, uno
evt[13]: 2, 2.2, dos
evt[14]: 3, 3.3, tres
evt[15]: 4, 4.4, quatro
Example (WithFormulaFromUser)

Code:play  

package main

import (
	"fmt"
	"log"

	"go-hep.org/x/hep/groot"
	"go-hep.org/x/hep/groot/rtree"
)

type UsrF64 struct {
	rvars []string
	v1    *int32
	v2    *float32
	v3    *string
	fct   func(int32, float32, string) float64
}

func (usr *UsrF64) RVars() []string { return usr.rvars }
func (usr *UsrF64) Bind(args []interface{}) error {
	if got, want := len(args), 3; got != want {
		return fmt.Errorf(
			"rfunc: invalid number of bind arguments (got=%d, want=%d)",
			got, want,
		)
	}
	usr.v1 = args[0].(*int32)
	usr.v2 = args[1].(*float32)
	usr.v3 = args[2].(*string)
	return nil
}

func (usr *UsrF64) Func() interface{} {
	return func() float64 {
		return usr.fct(*usr.v1, *usr.v2, *usr.v3)
	}
}

type UsrStr struct {
	rvars []string
	v1    *int32
	v2    *float32
	v3    *string
	fct   func(int32, float32, string) string
}

func (usr *UsrStr) RVars() []string { return usr.rvars }
func (usr *UsrStr) Bind(args []interface{}) error {
	if got, want := len(args), 3; got != want {
		return fmt.Errorf(
			"rfunc: invalid number of bind arguments (got=%d, want=%d)",
			got, want,
		)
	}
	usr.v1 = args[0].(*int32)
	usr.v2 = args[1].(*float32)
	usr.v3 = args[2].(*string)
	return nil
}

func (usr *UsrStr) Func() interface{} {
	return func() string {
		return usr.fct(*usr.v1, *usr.v2, *usr.v3)
	}
}

func main() {
	f, err := groot.Open("../testdata/simple.root")
	if err != nil {
		log.Fatalf("could not open ROOT file: %+v", err)
	}
	defer f.Close()

	o, err := f.Get("tree")
	if err != nil {
		log.Fatalf("could not retrieve ROOT tree: %+v", err)
	}
	t := o.(rtree.Tree)

	var (
		data struct {
			V1 int32   `groot:"one"`
			V2 float32 `groot:"two"`
			V3 string  `groot:"three"`
		}
		rvars = rtree.ReadVarsFromStruct(&data)
	)

	r, err := rtree.NewReader(t, rvars)
	if err != nil {
		log.Fatalf("could not create tree reader: %+v", err)
	}
	defer r.Close()

	f64, err := r.Formula(&UsrF64{
		rvars: []string{"one", "two", "three"},
		fct: func(v1 int32, v2 float32, v3 string) float64 {
			return float64(v2*10) + float64(1000*v1) + float64(100*len(v3))
		},
	})
	if err != nil {
		log.Fatalf("could not create formula: %+v", err)
	}

	fstr, err := r.Formula(&UsrStr{
		rvars: []string{"one", "two", "three"},
		fct: func(v1 int32, v2 float32, v3 string) string {
			return fmt.Sprintf(
				"%q: %v, %q: %v, %q: %v",
				"one", v1, "two", v2, "three", v3,
			)
		},
	})
	if err != nil {
		log.Fatalf("could not create formula: %+v", err)
	}

	f1 := f64.Func().(func() float64)
	f2 := fstr.Func().(func() string)

	err = r.Read(func(ctx rtree.RCtx) error {
		v64 := f1()
		str := f2()
		fmt.Printf("evt[%d]: %v, %v, %v -> %g | %s\n", ctx.Entry, data.V1, data.V2, data.V3, v64, str)
		return nil
	})
	if err != nil {
		log.Fatalf("could not process tree: %+v", err)
	}

}

Output:

evt[0]: 1, 1.1, uno -> 1311 | "one": 1, "two": 1.1, "three": uno
evt[1]: 2, 2.2, dos -> 2322 | "one": 2, "two": 2.2, "three": dos
evt[2]: 3, 3.3, tres -> 3433 | "one": 3, "two": 3.3, "three": tres
evt[3]: 4, 4.4, quatro -> 4644 | "one": 4, "two": 4.4, "three": quatro
Example (WithFormulaFunc)

Code:play  

package main

import (
	"fmt"
	"log"

	"go-hep.org/x/hep/groot"
	"go-hep.org/x/hep/groot/rtree"
)

func main() {
	f, err := groot.Open("../testdata/simple.root")
	if err != nil {
		log.Fatalf("could not open ROOT file: %+v", err)
	}
	defer f.Close()

	o, err := f.Get("tree")
	if err != nil {
		log.Fatalf("could not retrieve ROOT tree: %+v", err)
	}
	t := o.(rtree.Tree)

	var (
		data struct {
			V1 int32   `groot:"one"`
			V2 float32 `groot:"two"`
			V3 string  `groot:"three"`
		}
		rvars = rtree.ReadVarsFromStruct(&data)
	)

	r, err := rtree.NewReader(t, rvars)
	if err != nil {
		log.Fatalf("could not create tree reader: %+v", err)
	}
	defer r.Close()

	f64, err := r.FormulaFunc(
		[]string{"one", "two", "three"},
		func(v1 int32, v2 float32, v3 string) float64 {
			return float64(v2*10) + float64(1000*v1) + float64(100*len(v3))
		},
	)
	if err != nil {
		log.Fatalf("could not create formula: %+v", err)
	}

	fstr, err := r.FormulaFunc(
		[]string{"one", "two", "three"},
		func(v1 int32, v2 float32, v3 string) string {
			return fmt.Sprintf(
				"%q: %v, %q: %v, %q: %v",
				"one", v1, "two", v2, "three", v3,
			)
		},
	)
	if err != nil {
		log.Fatalf("could not create formula: %+v", err)
	}

	f1 := f64.Func().(func() float64)
	f2 := fstr.Func().(func() string)

	err = r.Read(func(ctx rtree.RCtx) error {
		v64 := f1()
		str := f2()
		fmt.Printf("evt[%d]: %v, %v, %v -> %g | %s\n", ctx.Entry, data.V1, data.V2, data.V3, v64, str)
		return nil
	})
	if err != nil {
		log.Fatalf("could not process tree: %+v", err)
	}

}

Output:

evt[0]: 1, 1.1, uno -> 1311 | "one": 1, "two": 1.1, "three": uno
evt[1]: 2, 2.2, dos -> 2322 | "one": 2, "two": 2.2, "three": dos
evt[2]: 3, 3.3, tres -> 3433 | "one": 3, "two": 3.3, "three": tres
evt[3]: 4, 4.4, quatro -> 4644 | "one": 4, "two": 4.4, "three": quatro
Example (WithRange)

Code:play  

package main

import (
	"fmt"
	"log"

	"go-hep.org/x/hep/groot"
	"go-hep.org/x/hep/groot/rtree"
)

func main() {
	f, err := groot.Open("../testdata/simple.root")
	if err != nil {
		log.Fatalf("could not open ROOT file: %+v", err)
	}
	defer f.Close()

	o, err := f.Get("tree")
	if err != nil {
		log.Fatalf("could not retrieve ROOT tree: %+v", err)
	}
	t := o.(rtree.Tree)

	var (
		v1 int32
		v2 float32
		v3 string

		rvars = []rtree.ReadVar{
			{Name: "one", Value: &v1},
			{Name: "two", Value: &v2},
			{Name: "three", Value: &v3},
		}
	)

	r, err := rtree.NewReader(t, rvars, rtree.WithRange(1, 3))
	if err != nil {
		log.Fatalf("could not create tree reader: %+v", err)
	}
	defer r.Close()

	err = r.Read(func(ctx rtree.RCtx) error {
		fmt.Printf("evt[%d]: %v, %v, %v\n", ctx.Entry, v1, v2, v3)
		return nil
	})
	if err != nil {
		log.Fatalf("could not process tree: %+v", err)
	}

}

Output:

evt[1]: 2, 2.2, dos
evt[2]: 3, 3.3, tres
Example (WithReadVarsFromStruct)

Code:play  

package main

import (
	"fmt"
	"log"

	"go-hep.org/x/hep/groot"
	"go-hep.org/x/hep/groot/rtree"
)

func main() {
	f, err := groot.Open("../testdata/simple.root")
	if err != nil {
		log.Fatalf("could not open ROOT file: %+v", err)
	}
	defer f.Close()

	o, err := f.Get("tree")
	if err != nil {
		log.Fatalf("could not retrieve ROOT tree: %+v", err)
	}
	t := o.(rtree.Tree)

	var (
		data struct {
			V1 int32   `groot:"one"`
			V2 float32 `groot:"two"`
			V3 string  `groot:"three"`
		}
		rvars = rtree.ReadVarsFromStruct(&data)
	)

	r, err := rtree.NewReader(t, rvars)
	if err != nil {
		log.Fatalf("could not create tree reader: %+v", err)
	}
	defer r.Close()

	err = r.Read(func(ctx rtree.RCtx) error {
		fmt.Printf("evt[%d]: %v, %v, %v\n", ctx.Entry, data.V1, data.V2, data.V3)
		return nil
	})
	if err != nil {
		log.Fatalf("could not process tree: %+v", err)
	}

}

Output:

evt[0]: 1, 1.1, uno
evt[1]: 2, 2.2, dos
evt[2]: 3, 3.3, tres
evt[3]: 4, 4.4, quatro
Example (WithReset)

Code:play  

package main

import (
	"fmt"
	"log"

	"go-hep.org/x/hep/groot"
	"go-hep.org/x/hep/groot/rtree"
)

func main() {
	f, err := groot.Open("../testdata/simple.root")
	if err != nil {
		log.Fatalf("could not open ROOT file: %+v", err)
	}
	defer f.Close()

	o, err := f.Get("tree")
	if err != nil {
		log.Fatalf("could not retrieve ROOT tree: %+v", err)
	}
	t := o.(rtree.Tree)

	var (
		v1 int32
		v2 float32
		v3 string

		rvars = []rtree.ReadVar{
			{Name: "one", Value: &v1},
			{Name: "two", Value: &v2},
			{Name: "three", Value: &v3},
		}
	)

	r, err := rtree.NewReader(t, rvars)
	if err != nil {
		log.Fatalf("could not create tree reader: %+v", err)
	}
	defer r.Close()

	err = r.Reset()
	if err != nil {
		log.Fatalf("could not reset tree reader: %+v", err)
	}

	err = r.Reset(rtree.WithRange(1, 3))
	if err != nil {
		log.Fatalf("could not reset tree reader: %+v", err)
	}

	err = r.Read(func(ctx rtree.RCtx) error {
		fmt.Printf("evt[%d]: %v, %v, %v\n", ctx.Entry, v1, v2, v3)
		return nil
	})
	if err != nil {
		log.Fatalf("could not process tree: %+v", err)
	}

}

Output:

evt[1]: 2, 2.2, dos
evt[2]: 3, 3.3, tres

func NewReader 

func NewReader(t Tree, rvars []ReadVar, opts ...ReadOption) (*Reader, error)

NewReader creates a new Tree Reader from the provided ROOT Tree and the set of read-variables into which data will be read.

func (*Reader) Close 

func (r *Reader) Close() error

Close closes the Reader.

func (*Reader) Formula 

func (r *Reader) Formula(f rfunc.Formula) (rfunc.Formula, error)

Formula creates a new formula based on the provided user provided formula. Formula binds the provided function with the requested list of leaves.

func (*Reader) FormulaFunc 

func (r *Reader) FormulaFunc(branches []string, fct interface{}) (rfunc.Formula, error)

FormulaFunc creates a new formula based on the provided function and the list of branches as inputs.

func (*Reader) Read 

func (r *Reader) Read(f func(ctx RCtx) error) error

Read will read data from the underlying tree over the whole specified range. Read calls the provided user function f for each entry successfully read.

func (*Reader) Reset 

func (r *Reader) Reset(opts ...ReadOption) error

Reset resets the current Reader with the provided options.

type Tree 

type Tree interface {
	root.Named

	Entries() int64
	Branch(name string) Branch
	Branches() []Branch
	Leaf(name string) Leaf
	Leaves() []Leaf
}

func Chain 

func Chain(trees ...Tree) Tree

Chain returns a Tree that is the concatenation of all the input Trees.

Example

ExampleChain shows how to create a chain made of 2 trees.

Code:play  

package main

import (
	"fmt"
	"log"

	"go-hep.org/x/hep/groot"
	"go-hep.org/x/hep/groot/rtree"
)

func main() {
	const name = "tree"

	f1, err := groot.Open("../testdata/chain.1.root")
	if err != nil {
		log.Fatal(err)
	}
	defer f1.Close()

	o1, err := f1.Get(name)
	if err != nil {
		log.Fatal(err)
	}
	t1 := o1.(rtree.Tree)

	f2, err := groot.Open("../testdata/chain.2.root")
	if err != nil {
		log.Fatal(err)
	}
	defer f2.Close()

	o2, err := f2.Get(name)
	if err != nil {
		log.Fatal(err)
	}
	t2 := o2.(rtree.Tree)

	chain := rtree.Chain(t1, t2)

	type Data struct {
		Event struct {
			Beg       string      `groot:"Beg"`
			F64       float64     `groot:"F64"`
			ArrF64    [10]float64 `groot:"ArrayF64"`
			N         int32       `groot:"N"`
			SliF64    []float64   `groot:"SliceF64"`
			StdStr    string      `groot:"StdStr"`
			StlVecF64 []float64   `groot:"StlVecF64"`
			StlVecStr []string    `groot:"StlVecStr"`
			End       string      `groot:"End"`
		} `groot:"evt"`
	}

	var data Data
	r, err := rtree.NewReader(chain, rtree.ReadVarsFromStruct(&data))
	if err != nil {
		log.Fatal(err)
	}
	defer r.Close()

	err = r.Read(func(ctx rtree.RCtx) error {
		fmt.Printf(
			"entry[%02d]: beg=%q f64=%v\n",
			ctx.Entry, data.Event.Beg, data.Event.F64,
		)
		return nil
	})

	if err != nil {
		log.Fatalf("error during scan: %v", err)
	}

}

Output:

entry[00]: beg="beg-000" f64=0
entry[01]: beg="beg-001" f64=1
entry[02]: beg="beg-002" f64=2
entry[03]: beg="beg-003" f64=3
entry[04]: beg="beg-004" f64=4
entry[05]: beg="beg-005" f64=5
entry[06]: beg="beg-006" f64=6
entry[07]: beg="beg-007" f64=7
entry[08]: beg="beg-008" f64=8
entry[09]: beg="beg-009" f64=9
entry[10]: beg="beg-010" f64=10
entry[11]: beg="beg-011" f64=11
entry[12]: beg="beg-012" f64=12
entry[13]: beg="beg-013" f64=13
entry[14]: beg="beg-014" f64=14
entry[15]: beg="beg-015" f64=15
entry[16]: beg="beg-016" f64=16
entry[17]: beg="beg-017" f64=17
entry[18]: beg="beg-018" f64=18
entry[19]: beg="beg-019" f64=19

func ChainOf 

func ChainOf(name string, files ...string) (Tree, func() error, error)

ChainOf returns a Tree, a close function and an error if any. The tree is the logical concatenation of all the name trees located in the input named files. The close function allows to close all the open named files.

Example

ExampleChainOf shows how to create a chain made of trees from 2 files.

Code:play  

package main

import (
	"fmt"
	"log"

	"go-hep.org/x/hep/groot/rtree"
)

func main() {
	const name = "tree"

	chain, closer, err := rtree.ChainOf(name, "../testdata/chain.1.root", "../testdata/chain.2.root")
	if err != nil {
		log.Fatal(err)
	}
	defer func() {
		err = closer()
		if err != nil {
			log.Fatalf("could not close ROOT chain: %+v", err)
		}
	}()

	type Data struct {
		Event struct {
			Beg       string      `groot:"Beg"`
			F64       float64     `groot:"F64"`
			ArrF64    [10]float64 `groot:"ArrayF64"`
			N         int32       `groot:"N"`
			SliF64    []float64   `groot:"SliceF64"`
			StdStr    string      `groot:"StdStr"`
			StlVecF64 []float64   `groot:"StlVecF64"`
			StlVecStr []string    `groot:"StlVecStr"`
			End       string      `groot:"End"`
		} `groot:"evt"`
	}

	var data Data
	r, err := rtree.NewReader(chain, rtree.ReadVarsFromStruct(&data))
	if err != nil {
		log.Fatal(err)
	}
	defer r.Close()

	err = r.Read(func(ctx rtree.RCtx) error {
		fmt.Printf(
			"entry[%02d]: beg=%q f64=%v\n",
			ctx.Entry, data.Event.Beg, data.Event.F64,
		)
		return nil
	})

	if err != nil {
		log.Fatalf("error during scan: %v", err)
	}

}

Output:

entry[00]: beg="beg-000" f64=0
entry[01]: beg="beg-001" f64=1
entry[02]: beg="beg-002" f64=2
entry[03]: beg="beg-003" f64=3
entry[04]: beg="beg-004" f64=4
entry[05]: beg="beg-005" f64=5
entry[06]: beg="beg-006" f64=6
entry[07]: beg="beg-007" f64=7
entry[08]: beg="beg-008" f64=8
entry[09]: beg="beg-009" f64=9
entry[10]: beg="beg-010" f64=10
entry[11]: beg="beg-011" f64=11
entry[12]: beg="beg-012" f64=12
entry[13]: beg="beg-013" f64=13
entry[14]: beg="beg-014" f64=14
entry[15]: beg="beg-015" f64=15
entry[16]: beg="beg-016" f64=16
entry[17]: beg="beg-017" f64=17
entry[18]: beg="beg-018" f64=18
entry[19]: beg="beg-019" f64=19

func Join 

func Join(trees ...Tree) (Tree, error)

Join returns a new Tree that represents the logical join of the input trees. The returned tree will contain all the columns of all the input trees. Join errors out if the input slice of trees is empty. Join errors out if the input trees do not have the same amount of entries. Join errors out if two trees have each a column with the same name.

Example

Code:play  

package main

import (
	"fmt"
	"log"

	"go-hep.org/x/hep/groot"
	"go-hep.org/x/hep/groot/rtree"
)

func main() {

	get := func(fname, tname string) (rtree.Tree, func() error) {
		f, err := groot.Open(fname)
		if err != nil {
			log.Fatal(err)
		}
		t, err := f.Get(tname)
		if err != nil {
			_ = f.Close()
			log.Fatal(err)
		}
		return t.(rtree.Tree), f.Close
	}
	chk := func(f func() error) {
		err := f()
		if err != nil {
			log.Fatal(err)
		}
	}

	t1, f1 := get("../testdata/join1.root", "j1")
	defer chk(f1)

	t2, f2 := get("../testdata/join2.root", "j2")
	defer chk(f2)

	t3, f3 := get("../testdata/join3.root", "j3")
	defer chk(f3)

	join, err := rtree.Join(t1, t2, t3)
	if err != nil {
		log.Fatalf("could not join trees: %+v", err)
	}

	fmt.Printf("t1:   %s (nevts=%d)\n", t1.Name(), t1.Entries())
	fmt.Printf("t2:   %s (nevts=%d)\n", t2.Name(), t2.Entries())
	fmt.Printf("t3:   %s (nevts=%d)\n", t3.Name(), t3.Entries())
	fmt.Printf("join: %s\n", join.Name())
	fmt.Printf("entries: %d\n", join.Entries())

	rvars := rtree.NewReadVars(join)
	r, err := rtree.NewReader(join, rvars)
	if err != nil {
		log.Fatalf("could not create reader for joined trees: %+v", err)
	}
	defer r.Close()

	rf1, err := r.FormulaFunc(
		[]string{"b10", "b30", "b20"},
		func(b1, b3, b2 float64) float64 {
			return b1 + b2 + b3
		},
	)
	if err != nil {
		log.Fatalf("could not bind formula: %+v", err)
	}
	fct1 := rf1.Func().(func() float64)

	err = r.Read(func(rctx rtree.RCtx) error {
		for _, rv := range rvars {
			fmt.Printf("join[%03d][%s]: %v\n", rctx.Entry, rv.Name, rv.Deref())
		}
		fmt.Printf("join[%03d][fun]: %v\n", rctx.Entry, fct1())
		return nil
	})

	if err != nil {
		log.Fatalf("could not process events: %+v", err)
	}

}

Output:

t1:   j1 (nevts=10)
t2:   j2 (nevts=10)
t3:   j3 (nevts=10)
join: join_j1_j2_j3
entries: 10
join[000][b10]: 101
join[000][b11]: 101
join[000][b12]: j1-101
join[000][b20]: 201
join[000][b21]: 201
join[000][b22]: j2-201
join[000][b30]: 301
join[000][b31]: 301
join[000][b32]: j3-301
join[000][fun]: 603
join[001][b10]: 102
join[001][b11]: 102
join[001][b12]: j1-102
join[001][b20]: 202
join[001][b21]: 202
join[001][b22]: j2-202
join[001][b30]: 302
join[001][b31]: 302
join[001][b32]: j3-302
join[001][fun]: 606
join[002][b10]: 103
join[002][b11]: 103
join[002][b12]: j1-103
join[002][b20]: 203
join[002][b21]: 203
join[002][b22]: j2-203
join[002][b30]: 303
join[002][b31]: 303
join[002][b32]: j3-303
join[002][fun]: 609
join[003][b10]: 104
join[003][b11]: 104
join[003][b12]: j1-104
join[003][b20]: 204
join[003][b21]: 204
join[003][b22]: j2-204
join[003][b30]: 304
join[003][b31]: 304
join[003][b32]: j3-304
join[003][fun]: 612
join[004][b10]: 105
join[004][b11]: 105
join[004][b12]: j1-105
join[004][b20]: 205
join[004][b21]: 205
join[004][b22]: j2-205
join[004][b30]: 305
join[004][b31]: 305
join[004][b32]: j3-305
join[004][fun]: 615
join[005][b10]: 106
join[005][b11]: 106
join[005][b12]: j1-106
join[005][b20]: 206
join[005][b21]: 206
join[005][b22]: j2-206
join[005][b30]: 306
join[005][b31]: 306
join[005][b32]: j3-306
join[005][fun]: 618
join[006][b10]: 107
join[006][b11]: 107
join[006][b12]: j1-107
join[006][b20]: 207
join[006][b21]: 207
join[006][b22]: j2-207
join[006][b30]: 307
join[006][b31]: 307
join[006][b32]: j3-307
join[006][fun]: 621
join[007][b10]: 108
join[007][b11]: 108
join[007][b12]: j1-108
join[007][b20]: 208
join[007][b21]: 208
join[007][b22]: j2-208
join[007][b30]: 308
join[007][b31]: 308
join[007][b32]: j3-308
join[007][fun]: 624
join[008][b10]: 109
join[008][b11]: 109
join[008][b12]: j1-109
join[008][b20]: 209
join[008][b21]: 209
join[008][b22]: j2-209
join[008][b30]: 309
join[008][b31]: 309
join[008][b32]: j3-309
join[008][fun]: 627
join[009][b10]: 110
join[009][b11]: 110
join[009][b12]: j1-110
join[009][b20]: 210
join[009][b21]: 210
join[009][b22]: j2-210
join[009][b30]: 310
join[009][b31]: 310
join[009][b32]: j3-310
join[009][fun]: 630
Example (WithReadVarSelection)

Code:play  

package main

import (
	"fmt"
	"log"
	"strings"

	"go-hep.org/x/hep/groot"
	"go-hep.org/x/hep/groot/rtree"
)

func main() {

	get := func(fname, tname string) (rtree.Tree, func() error) {
		f, err := groot.Open(fname)
		if err != nil {
			log.Fatal(err)
		}
		t, err := f.Get(tname)
		if err != nil {
			_ = f.Close()
			log.Fatal(err)
		}
		return t.(rtree.Tree), f.Close
	}
	chk := func(f func() error) {
		err := f()
		if err != nil {
			log.Fatal(err)
		}
	}

	t1, f1 := get("../testdata/join1.root", "j1")
	defer chk(f1)

	t2, f2 := get("../testdata/join2.root", "j2")
	defer chk(f2)

	t3, f3 := get("../testdata/join3.root", "j3")
	defer chk(f3)

	join, err := rtree.Join(t1, t2, t3)
	if err != nil {
		log.Fatalf("could not join trees: %+v", err)
	}

	fmt.Printf("t1:   %s (nevts=%d)\n", t1.Name(), t1.Entries())
	fmt.Printf("t2:   %s (nevts=%d)\n", t2.Name(), t2.Entries())
	fmt.Printf("t3:   %s (nevts=%d)\n", t3.Name(), t3.Entries())
	fmt.Printf("join: %s\n", join.Name())
	fmt.Printf("entries: %d\n", join.Entries())

	rvars := []rtree.ReadVar{
		{Name: "b10", Value: new(float64)},
		{Name: "b20", Value: new(float64)},
	}

	r, err := rtree.NewReader(join, rvars, rtree.WithRange(3, 8))
	if err != nil {
		log.Fatalf("could not create reader for joined trees: %+v", err)
	}
	defer r.Close()

	rf1, err := r.FormulaFunc(
		[]string{"b12", "b32", "b22"},
		func(b1, b3, b2 string) string {
			return strings.Join([]string{b1, b3, b2}, ", ")
		},
	)
	if err != nil {
		log.Fatalf("could not bind formula: %+v", err)
	}
	fct1 := rf1.Func().(func() string)

	err = r.Read(func(rctx rtree.RCtx) error {
		for _, rv := range rvars {
			fmt.Printf("join[%03d][%s]: %v\n", rctx.Entry, rv.Name, rv.Deref())
		}
		fmt.Printf("join[%03d][fun]: %v\n", rctx.Entry, fct1())
		return nil
	})

	if err != nil {
		log.Fatalf("could not process events: %+v", err)
	}

}

Output:

t1:   j1 (nevts=10)
t2:   j2 (nevts=10)
t3:   j3 (nevts=10)
join: join_j1_j2_j3
entries: 10
join[003][b10]: 104
join[003][b20]: 204
join[003][fun]: j1-104, j3-304, j2-204
join[004][b10]: 105
join[004][b20]: 205
join[004][fun]: j1-105, j3-305, j2-205
join[005][b10]: 106
join[005][b20]: 206
join[005][fun]: j1-106, j3-306, j2-206
join[006][b10]: 107
join[006][b20]: 207
join[006][fun]: j1-107, j3-307, j2-207
join[007][b10]: 108
join[007][b20]: 208
join[007][fun]: j1-108, j3-308, j2-208

type WriteOption 

type WriteOption func(opt *wopt) error

WriteOption configures how a ROOT tree (and its branches) should be created.

func WithBasketSize 

func WithBasketSize(size int) WriteOption

WithBasketSize configures a ROOT tree to use 'size' (in bytes) as a basket buffer size. if size is <= 0, the default buffer size is used (DefaultBasketSize).

func WithLZ4 

func WithLZ4(level int) WriteOption

WithLZ4 configures a ROOT tree to use LZ4 as a compression mechanism.

func WithLZMA 

func WithLZMA(level int) WriteOption

WithLZMA configures a ROOT tree to use LZMA as a compression mechanism.

func WithSplitLevel 

func WithSplitLevel(lvl int) WriteOption

WithSplitLevel sets the maximum branch depth split level

func WithTitle 

func WithTitle(title string) WriteOption

WithTitle sets the title of the tree writer.

func WithZlib 

func WithZlib(level int) WriteOption

WithZlib configures a ROOT tree to use zlib as a compression mechanism.

func WithZstd 

func WithZstd(level int) WriteOption

WithZstd configures a ROOT tree to use zstd as a compression mechanism.

func WithoutCompression 

func WithoutCompression() WriteOption

WithoutCompression configures a ROOT tree to not use any compression mechanism.

type WriteVar 

type WriteVar struct {
	Name  string      // name of the variable
	Value interface{} // pointer to the value to write
	Count string      // name of the branch holding the count-leaf value for slices
}

WriteVar describes a variable to be written out to a tree.

func WriteVarsFromStruct 

func WriteVarsFromStruct(ptr interface{}, opts ...WriteOption) []WriteVar

WriteVarsFromStruct creates a slice of WriteVars from the ptr value. WriteVarsFromStruct panics if ptr is not a pointer to a struct value. WriteVarsFromStruct ignores fields that are not exported.

func WriteVarsFromTree 

func WriteVarsFromTree(t Tree) []WriteVar

WriteVarsFromTree creates a slice of WriteVars from the tree value.

type Writer 

type Writer interface {
	Tree

	// Write writes the event data to ROOT storage and returns the number
	// of bytes (before compression, if any) written.
	Write() (int, error)

	// Flush commits the current contents of the tree to stable storage.
	Flush() error

	// Close writes metadata and closes the tree.
	Close() error
}

Writer is the interface that wraps the Write method for Trees.

func NewWriter 

func NewWriter(dir riofs.Directory, name string, vars []WriteVar, opts ...WriteOption) (Writer, error)

NewWriter creates a new Tree with the given name and under the given directory dir, ready to be filled with data.

Source Files

basket.go bkreader.go branch.go chain.go copy.go formula.go join.go leaf.go leaf_gen.go rbasket.go rbranch.go rchain.go reader.go rjoin.go rleaf.go rleaf_gen.go rtree.go rvar.go tree.go writer.go wvar.go

Directories

PathSynopsis
groot/rtree/rfuncPackage rfunc provides types and funcs to implement user-provided formulae evaluated on data exposed by ROOT trees.
Version
v0.36.0 (latest)
Published
Nov 15, 2024
Platform
linux/amd64
Imports
21 packages
Last checked
1 day ago –

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