rsql

package
v0.38.1 Latest Latest
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 Go to latest Published: Oct 30, 2025 License: BSD-3-Clause Imports: 7 Imported by: 0

Documentation

Overview

Package rsql provides a convenient access to ROOT files/trees as a database.

Index

Examples

Constants

This section is empty.

Variables

This section is empty.

Functions

func Scan 

func Scan(tree rtree.Tree, query string, f any) error

Scan executes a query against the given tree and runs the function f within that context.

Example 
package main

import (
	"fmt"
	"log"

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

func main() {
	f, err := groot.Open("../testdata/simple.root")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	o, err := f.Get("tree")
	if err != nil {
		log.Fatal(err)
	}

	tree := o.(rtree.Tree)

	var data []float64

	err = rsql.Scan(tree, "SELECT two FROM tree", func(x float64) error {
		data = append(data, x)
		return nil
	})

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

	fmt.Printf("tree[%q]: %v\n", "two", data)

}

Output:
tree["two"]: [1.1 2.2 3.3 4.4]
Example (NVars) 
package main

import (
	"fmt"
	"log"

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

func main() {
	f, err := groot.Open("../testdata/simple.root")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	o, err := f.Get("tree")
	if err != nil {
		log.Fatal(err)
	}

	tree := o.(rtree.Tree)

	var (
		v1s []int32
		v2s []float64
		v3s []string
	)

	err = rsql.Scan(tree, "SELECT (one, two, three) FROM tree", func(x int32, y float64, z string) error {
		v1s = append(v1s, x)
		v2s = append(v2s, y)
		v3s = append(v3s, z)
		return nil
	})

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

	fmt.Printf("tree[%q]: %v\n", "one", v1s)
	fmt.Printf("tree[%q]: %v\n", "two", v2s)
	fmt.Printf("tree[%q]: %q\n", "three", v3s)

}

Output:
tree["one"]: [1 2 3 4]
tree["two"]: [1.1 2.2 3.3 4.4]
tree["three"]: ["uno" "dos" "tres" "quatro"]

func ScanH1D 

func ScanH1D(tree rtree.Tree, query string, h *hbook.H1D) (*hbook.H1D, error)

ScanH1D executes a query against the tree and fills the histogram with the results of the query. If h is nil, a (100-bins, xmin, xmax+ULP) histogram is created, where xmin and xmax are inferred from the content of the underlying database.

Example 
package main

import (
	"fmt"
	"log"

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

func main() {
	f, err := groot.Open("../testdata/simple.root")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	o, err := f.Get("tree")
	if err != nil {
		log.Fatal(err)
	}

	tree := o.(rtree.Tree)

	h, err := rsql.ScanH1D(tree, "SELECT two FROM tree", nil)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("entries: %v\n", h.Entries())
	fmt.Printf("x-axis: (min=%v, max=%v)\n", h.XMin(), h.XMax())
	fmt.Printf("x-mean: %v\n", h.XMean())
	fmt.Printf("x-std-dev: %1.3f\nx-std-err: %1.3f\n", h.XStdDev(), h.XStdErr())

}

Output:
entries: 4
x-axis: (min=1.1, max=4.400000000000001)
x-mean: 2.75
x-std-dev: 1.420
x-std-err: 0.710
Example (WithH1D) 
package main

import (
	"fmt"
	"log"

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

func main() {
	f, err := groot.Open("../testdata/simple.root")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	o, err := f.Get("tree")
	if err != nil {
		log.Fatal(err)
	}

	tree := o.(rtree.Tree)

	h, err := rsql.ScanH1D(tree, "SELECT two FROM tree", hbook.NewH1D(100, 0, 10))
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("entries: %v\n", h.Entries())
	fmt.Printf("x-axis: (min=%v, max=%v)\n", h.XMin(), h.XMax())
	fmt.Printf("x-mean: %v\n", h.XMean())
	fmt.Printf("x-std-dev: %1.3f\nx-std-err: %1.3f\n", h.XStdDev(), h.XStdErr())

}

Output:
entries: 4
x-axis: (min=0, max=10)
x-mean: 2.75
x-std-dev: 1.420
x-std-err: 0.710

func ScanH2D 

func ScanH2D(tree rtree.Tree, query string, h *hbook.H2D) (*hbook.H2D, error)

ScanH2D executes a query against the ntuple and fills the histogram with the results of the query. If h is nil, a (100-bins, xmin, xmax+ULP) (100-bins, ymin, ymax+ULP) 2d-histogram is created, where xmin, xmax and ymin,ymax are inferred from the content of the underlying database.

Example 
package main

import (
	"fmt"
	"log"

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

func main() {
	f, err := groot.Open("../testdata/simple.root")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	o, err := f.Get("tree")
	if err != nil {
		log.Fatal(err)
	}

	tree := o.(rtree.Tree)

	h, err := rsql.ScanH2D(tree, "SELECT (one, two) FROM tree", nil)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("entries: %v\n", h.Entries())
	fmt.Printf("x-axis: (min=%v, max=%v)\n", h.XMin(), h.XMax())
	fmt.Printf("x-mean: %v\n", h.XMean())
	fmt.Printf("x-std-dev: %1.3f\nx-std-err: %1.3f\n", h.XStdDev(), h.XStdErr())
	fmt.Printf("y-axis: (min=%v, max=%v)\n", h.YMin(), h.YMax())
	fmt.Printf("y-mean: %v\n", h.YMean())
	fmt.Printf("y-std-dev: %1.3f\ny-std-err: %1.3f\n", h.YStdDev(), h.YStdErr())

}

Output:
entries: 4
x-axis: (min=1, max=4.000000000000001)
x-mean: 2.5
x-std-dev: 1.291
x-std-err: 0.645
y-axis: (min=1.1, max=4.400000000000001)
y-mean: 2.75
y-std-dev: 1.420
y-std-err: 0.710
Example (WithH2D) 
package main

import (
	"fmt"
	"log"

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

func main() {
	f, err := groot.Open("../testdata/simple.root")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	o, err := f.Get("tree")
	if err != nil {
		log.Fatal(err)
	}

	tree := o.(rtree.Tree)

	h, err := rsql.ScanH2D(tree, "SELECT (one, two) FROM tree", hbook.NewH2D(100, 0, 10, 100, 0, 10))
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("entries: %v\n", h.Entries())
	fmt.Printf("x-axis: (min=%v, max=%v)\n", h.XMin(), h.XMax())
	fmt.Printf("x-mean: %v\n", h.XMean())
	fmt.Printf("x-std-dev: %1.3f\nx-std-err: %1.3f\n", h.XStdDev(), h.XStdErr())
	fmt.Printf("y-axis: (min=%v, max=%v)\n", h.YMin(), h.YMax())
	fmt.Printf("y-mean: %v\n", h.YMean())
	fmt.Printf("y-std-dev: %1.3f\ny-std-err: %1.3f\n", h.YStdDev(), h.YStdErr())

}

Output:
entries: 4
x-axis: (min=0, max=10)
x-mean: 2.5
x-std-dev: 1.291
x-std-err: 0.645
y-axis: (min=0, max=10)
y-mean: 2.75
y-std-dev: 1.420
y-std-err: 0.710

Types

This section is empty.

Source Files

View all Source files

Directories

Path Synopsis
Package rsqldrv registers a database/sql/driver.Driver implementation for ROOT files.
 Package rsqldrv registers a database/sql/driver.Driver implementation for ROOT files.

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