dframe/dfmat: first import

dframe/dfmat/dfmat.go

@@ -0,0 +1,142 @@
+// Copyright ©2019 The Gonum Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package dfmat provides a set of tools to easily leverage gonum/mat types
+// from exp/dframe (and vice versa.)
+//
+// This is still a WIP package, building on the experience from:
+// - https://github.com/kniren/gota
+// - https://github.com/tobgu/qframe
+// Ultimately, dframe should also allow for a good inter-operability with
+// Apache Arrow:
+// - https://godoc.org/github.com/apache/arrow/go/arrow
+package dfmat // import "gonum.org/v1/exp/dframe/dfmat"
+
+import (
+	"fmt"
+
+	"github.com/apache/arrow/go/arrow"
+	"github.com/apache/arrow/go/arrow/array"
+	"github.com/apache/arrow/go/arrow/memory"
+	"gonum.org/v1/exp/dframe"
+	"gonum.org/v1/gonum/mat"
+)
+
+type Option func(c *config)
+
+// WithNames configures a dframe.Frame with the provided set of column names.
+func WithNames(names ...string) Option {
+	return func(c *config) {
+		c.names = make([]string, len(names))
+		copy(c.names, names)
+	}
+}
+
+type config struct {
+	names []string
+}
+
+func newConfig(n int) *config {
+	cfg := config{names: make([]string, n)}
+	for i := range cfg.names {
+		cfg.names[i] = fmt.Sprintf("col-%03d", i+1)
+	}
+	return &cfg
+}
+
+// FromMatrix creates a new dframe.Frame from a gonum/mat.Matrix.
+func FromMatrix(m mat.Matrix, opts ...Option) *dframe.Frame {
+	var (
+		mem = memory.NewGoAllocator()
+		bld = array.NewFloat64Builder(mem)
+
+		r, c   = m.Dims()
+		arrs   = make([]array.Interface, c)
+		fields = make([]arrow.Field, c)
+	)
+	defer bld.Release()
+
+	cfg := newConfig(c)
+	for _, opt := range opts {
+		opt(cfg)
+	}
+
+	switch m := m.(type) {
+	case mat.RawColViewer:
+		for i := 0; i < c; i++ {
+			col := m.RawColView(i)
+			bld.AppendValues(col, nil)
+			arrs[i] = bld.NewArray()
+			fields[i] = arrow.Field{
+				Name: cfg.names[i],
+				Type: arrs[i].DataType(),
+			}
+		}
+	default:
+		for i := 0; i < c; i++ {
+			for j := 0; j < r; j++ {
+				bld.Append(m.At(j, i))
+			}
+			arrs[i] = bld.NewArray()
+			fields[i] = arrow.Field{
+				Name: cfg.names[i],
+				Type: arrs[i].DataType(),
+			}
+		}
+	}
+
+	schema := arrow.NewSchema(fields, nil)
+	df, err := dframe.FromArrays(schema, arrs)
+	if err != nil {
+		panic(err)
+	}
+
+	return df
+}
+
+// FromVector creates a new dframe.Frame from a gonum/mat.Vector.
+func FromVector(vec mat.Vector, opts ...Option) *dframe.Frame {
+	var (
+		mem = memory.NewGoAllocator()
+		bld = array.NewFloat64Builder(mem)
+
+		rows   = vec.Len()
+		arrs   = make([]array.Interface, 1)
+		fields = make([]arrow.Field, 1)
+	)
+	defer bld.Release()
+
+	cfg := newConfig(1)
+	for _, opt := range opts {
+		opt(cfg)
+	}
+
+	switch vec := vec.(type) {
+	case mat.RawColViewer:
+		col := vec.RawColView(0)
+		bld.AppendValues(col, nil)
+		arrs[0] = bld.NewArray()
+		fields[0] = arrow.Field{
+			Name: cfg.names[0],
+			Type: arrs[0].DataType(),
+		}
+	default:
+		for i := 0; i < rows; i++ {
+			bld.Append(vec.AtVec(i))
+		}
+		arrs[0] = bld.NewArray()
+		fields[0] = arrow.Field{
+			Name: cfg.names[0],
+			Type: arrs[0].DataType(),
+		}
+	}
+
+	schema := arrow.NewSchema(fields, nil)
+	df, err := dframe.FromArrays(schema, arrs)
+	if err != nil {
+		panic(err)
+	}
+
+	return df
+}

dframe/dfmat/dfmat_example_test.go

@@ -0,0 +1,98 @@
+// Copyright ©2019 The Gonum Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package dfmat_test
+
+import (
+	"fmt"
+
+	"github.com/apache/arrow/go/arrow/array"
+
+	"gonum.org/v1/exp/dframe/dfmat"
+	"gonum.org/v1/gonum/mat"
+)
+
+func Example_fromMatrix() {
+	m := mat.NewDense(3, 2, []float64{
+		1, 2,
+		3, 4,
+		5, 6,
+	})
+
+	{
+		df := dfmat.FromMatrix(m, dfmat.WithNames("x", "y"))
+		defer df.Release()
+
+		fmt.Printf("cols: %v\n", df.ColumnNames())
+
+		tr := array.NewTableReader(df, -1)
+		defer tr.Release()
+
+		n := 0
+		for tr.Next() {
+			rec := tr.Record()
+			for i, col := range rec.Columns() {
+				fmt.Printf("rec[%d][%q]: %v\n", n, rec.ColumnName(i), col)
+			}
+			n++
+		}
+	}
+
+	{
+		df := dfmat.FromMatrix(m.T(), dfmat.WithNames("x", "y", "z"))
+		defer df.Release()
+
+		fmt.Printf("cols: %v\n", df.ColumnNames())
+
+		tr := array.NewTableReader(df, -1)
+		defer tr.Release()
+
+		n := 0
+		for tr.Next() {
+			rec := tr.Record()
+			for i, col := range rec.Columns() {
+				fmt.Printf("rec[%d][%q]: %v\n", n, rec.ColumnName(i), col)
+			}
+			n++
+		}
+	}
+
+	// Output:
+	// cols: [x y]
+	// rec[0]["x"]: [1 3 5]
+	// rec[0]["y"]: [2 4 6]
+	// cols: [x y z]
+	// rec[0]["x"]: [1 2]
+	// rec[0]["y"]: [3 4]
+	// rec[0]["z"]: [5 6]
+}
+
+func Example_fromVector() {
+	m := mat.NewVecDense(6, []float64{
+		1, 2,
+		3, 4,
+		5, 6,
+	})
+
+	df := dfmat.FromVector(m, dfmat.WithNames("x"))
+	defer df.Release()
+
+	fmt.Printf("cols: %v\n", df.ColumnNames())
+
+	tr := array.NewTableReader(df, -1)
+	defer tr.Release()
+
+	n := 0
+	for tr.Next() {
+		rec := tr.Record()
+		for i, col := range rec.Columns() {
+			fmt.Printf("rec[%d][%q]: %v\n", n, rec.ColumnName(i), col)
+		}
+		n++
+	}
+
+	// Output:
+	// cols: [x]
+	// rec[0]["x"]: [1 2 3 4 5 6]
+}