npyio provides read/write access to numpy data files.
Is done via go get:
$> go get github.com/sbinet/npyioIs available on godoc
npyio-ls is a command using github.com/sbinet/npyio (located under
github.com/sbinet/npyio/cmd/npyio-ls) to display the content of a (list of)
NumPy data file(s).
$> npyio-ls testdata/data_float64_2x3_?order.npy
================================================================================
file: testdata/data_float64_2x3_corder.npy
npy-header: Header{Major:1, Minor:0, Descr:{Type:<f8, Fortran:false, Shape:[2 3]}}
data = [0 1 2 3 4 5]
================================================================================
file: testdata/data_float64_2x3_forder.npy
npy-header: Header{Major:1, Minor:0, Descr:{Type:<f8, Fortran:true, Shape:[2 3]}}
data = [0 1 2 3 4 5]
$> npyio-ls testdata/data_float64_2x3x4_corder.npy
================================================================================
file: testdata/data_float64_2x3x4_corder.npy
npy-header: Header{Major:1, Minor:0, Descr:{Type:<f8, Fortran:false, Shape:[2 3 4]}}
data = [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23]
npyio-ls automatically detects .npz archive files and inspects them too:
$> npyio-ls testdata/data_float64_corder.npz
================================================================================
file: testdata/data_float64_corder.npz
entry: arr1.npy
npy-header: Header{Major:1, Minor:0, Descr:{Type:<f8, Fortran:false, Shape:[6 1]}}
data = [0 1 2 3 4 5]
entry: arr0.npy
npy-header: Header{Major:1, Minor:0, Descr:{Type:<f8, Fortran:false, Shape:[2 3]}}
data = [0 1 2 3 4 5]
Consider a .npy file created with the following python code:
>>> import numpy as np
>>> arr = np.arange(6, dtype="float64").reshape(2,3)
>>> f = open("data.npy", "w")
>>> np.save(f, arr)
>>> f.close()The (float64) data array can be loaded into a (float64) mat.Matrix by the following code:
package main
import (
"fmt"
"log"
"os"
"github.com/sbinet/npyio"
"gonum.org/v1/gonum/mat"
)
func main() {
f, err := os.Open(os.Args[1])
if err != nil {
log.Fatal(err)
}
defer f.Close()
r, err := npyio.NewReader(f)
if err != nil {
log.Fatal(err)
}
fmt.Printf("npy-header: %v\n", r.Header)
shape := r.Header.Descr.Shape
raw := make([]float64, shape[0]*shape[1])
err = r.Read(&raw)
if err != nil {
log.Fatal(err)
}
m := mat.NewDense(shape[0], shape[1], raw)
fmt.Printf("data = %v\n", mat.Formatted(m, mat.Prefix(" ")))
}$> my-binary data.npy
npy-header: Header{Major:1, Minor:0, Descr:{Type:<i8, Fortran:false, Shape:[2 3]}}
data = ⎡0 1 2⎤
⎣3 4 5⎦
Alternatively, one can use the convenience function npyio.Read:
package main
import (
"fmt"
"log"
"os"
"github.com/sbinet/npyio"
)
func main() {
f, err := os.Open(os.Args[1])
if err != nil {
log.Fatal(err)
}
defer f.Close()
var m []float64
err = npyio.Read(f, &m)
if err != nil {
log.Fatal(err)
}
fmt.Printf("data = %v\n", m)
}$> my-binary ./data.npy
data = [0 1 2 3 4 5]
package main
import (
"log"
"os"
"github.com/sbinet/npyio"
)
func main() {
f, err := os.Create("data.npy")
if err != nil {
log.Fatal(err)
}
defer f.Close()
m := []float64{0, 1, 2, 3, 4, 5}
err = npyio.Write(f, m)
if err != nil {
log.Fatalf("error writing to file: %v\n", err)
}
err = f.Close()
if err != nil {
log.Fatalf("error closing file: %v\n", err)
}
}func ExampleOpen() {
f, err := npz.Open("../testdata/data_float64_corder.npz")
if err != nil {
log.Fatalf("could not open npz file: %+v", err)
}
defer f.Close()
for _, name := range f.Keys() {
fmt.Printf("%s: %v\n", name, f.Header(name))
}
var f0 []float64
err = f.Read("arr0.npy", &f0)
if err != nil {
log.Fatalf("could not read value from npz file: %+v", err)
}
var f1 []float64
err = f.Read("arr1.npy", &f1)
if err != nil {
log.Fatalf("could not read value from npz file: %+v", err)
}
fmt.Printf("arr0: %v\n", f0)
fmt.Printf("arr1: %v\n", f1)
// Output:
// arr0.npy: Header{Major:1, Minor:0, Descr:{Type:<f8, Fortran:false, Shape:[2 3]}}
// arr1.npy: Header{Major:1, Minor:0, Descr:{Type:<f8, Fortran:false, Shape:[6 1]}}
// arr0: [0 1 2 3 4 5]
// arr1: [0 1 2 3 4 5]
}func ExampleReader() {
f, err := os.Open("../testdata/data_float64_corder.npz")
if err != nil {
log.Fatalf("could not open npz file: %+v", err)
}
defer f.Close()
stat, err := f.Stat()
if err != nil {
log.Fatalf("could not stat npz file: %+v", err)
}
r, err := npz.NewReader(f, stat.Size())
if err != nil {
log.Fatalf("could not open npz archive: %+v", err)
}
for _, name := range r.Keys() {
fmt.Printf("%s: %v\n", name, r.Header(name))
}
var f0 []float64
err = r.Read("arr0.npy", &f0)
if err != nil {
log.Fatalf("could not read value from npz file: %+v", err)
}
var f1 []float64
err = r.Read("arr1.npy", &f1)
if err != nil {
log.Fatalf("could not read value from npz file: %+v", err)
}
fmt.Printf("arr0: %v\n", f0)
fmt.Printf("arr1: %v\n", f1)
// Output:
// arr0.npy: Header{Major:1, Minor:0, Descr:{Type:<f8, Fortran:false, Shape:[2 3]}}
// arr1.npy: Header{Major:1, Minor:0, Descr:{Type:<f8, Fortran:false, Shape:[6 1]}}
// arr0: [0 1 2 3 4 5]
// arr1: [0 1 2 3 4 5]
}func ExampleRead() {
f, err := os.Open("../testdata/data_float64_corder.npz")
if err != nil {
log.Fatalf("could not open npz file: %+v", err)
}
defer f.Close()
var f0 []float64
err = npz.Read(f, "arr0.npy", &f0)
if err != nil {
log.Fatalf("could not read value from npz file: %+v", err)
}
var f1 []float64
err = npz.Read(f, "arr1.npy", &f1)
if err != nil {
log.Fatalf("could not read value from npz file: %+v", err)
}
fmt.Printf("arr0: %v\n", f0)
fmt.Printf("arr1: %v\n", f1)
// Output:
// arr0: [0 1 2 3 4 5]
// arr1: [0 1 2 3 4 5]
}func ExampleCreate() {
f, err := npz.Create("out.npz")
if err != nil {
log.Fatalf("could not create npz file: %+v", err)
}
defer f.Close()
err = f.Write("arr0.npy", []float64{0, 1, 2, 3, 4, 5})
if err != nil {
log.Fatalf("could not write value arr0.npy to npz file: %+v", err)
}
err = f.Write("arr1.npy", []float32{0, 1, 2, 3, 4, 5})
if err != nil {
log.Fatalf("could not write value arr1.npy to npz file: %+v", err)
}
err = f.Close()
if err != nil {
log.Fatalf("could not close npz file: %+v", err)
}
// Output:
}func ExampleWriter() {
f, err := os.Create("out.npz")
if err != nil {
log.Fatalf("could not create npz file: %+v", err)
}
defer f.Close()
wz := npz.NewWriter(f)
defer wz.Close()
err = wz.Write("arr0.npy", []float64{0, 1, 2, 3, 4, 5})
if err != nil {
log.Fatalf("could not write value arr0.npy to npz file: %+v", err)
}
err = wz.Write("arr1.npy", []float32{0, 1, 2, 3, 4, 5})
if err != nil {
log.Fatalf("could not write value arr1.npy to npz file: %+v", err)
}
err = wz.Close()
if err != nil {
log.Fatalf("could not close npz archive: %+v", err)
}
err = f.Close()
if err != nil {
log.Fatalf("could not close npz file: %+v", err)
}
// Output:
}func ExampleWrite() {
err := npz.Write("out.npz", map[string]interface{}{
"arr0.npy": []float64{0, 1, 2, 3, 4, 5},
"arr1.npy": []float32{0, 1, 2, 3, 4, 5},
})
if err != nil {
log.Fatalf("could not save to npz file: %+v", err)
}
// Output:
}