Added data importer module

Author: mpraski

data/test.csv

@@ -0,0 +1,3 @@
+0.1,0.2,0.3
+0.4,0.5,0.6
+0.7,0.8,0.9

importer.go

@@ -0,0 +1,84 @@
+package clusters
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/csv"
+	"io"
+	"os"
+	"strconv"
+)
+
+type Importer struct {
+}
+
+func NewImporter() *Importer {
+	return &Importer{}
+}
+
+func (i *Importer) Import(file string) ([][]float64, error) {
+	f, err := os.Open(file)
+	if err != nil {
+		return [][]float64{}, err
+	}
+
+	defer f.Close()
+
+	c, err := i.lineCount(bufio.NewReader(f))
+	if err != nil {
+		return [][]float64{}, err
+	}
+
+	f.Seek(0, 0)
+
+	var (
+		d = make([][]float64, c)
+		r = csv.NewReader(f)
+		k = 0
+	)
+
+	for {
+		record, err := r.Read()
+
+		if err == io.EOF {
+			break
+		} else if err != nil {
+			return [][]float64{}, err
+		}
+
+		d[k] = make([]float64, 0, len(record))
+
+		for j, _ := range record {
+			f, err := strconv.ParseFloat(record[j], 64)
+			if err == nil {
+				d[k] = append(d[k], f)
+			} else {
+				return [][]float64{}, err
+			}
+		}
+
+		k++
+	}
+
+	return d, nil
+}
+
+func (*Importer) lineCount(r *bufio.Reader) (int, error) {
+	var (
+		buf     = make([]byte, 32*1024)
+		count   = 0
+		lineSep = []byte{'\n'}
+	)
+
+	for {
+		c, err := r.Read(buf)
+		count += bytes.Count(buf[:c], lineSep)
+
+		switch err {
+		case io.EOF:
+			return count, nil
+		default:
+			return count, err
+		}
+	}
+}

importer_test.go

@@ -0,0 +1,66 @@
+package clusters
+
+import (
+	"math"
+	"testing"
+)
+
+const TOLERANCE = 0.000001
+
+func TestImportedLoadDataOfCorrectLengh(t *testing.T) {
+	var (
+		f = "data/test.csv"
+		i = NewImporter()
+		s = 3
+	)
+
+	d, e := i.Import(f)
+	if e != nil {
+		t.Errorf("Error importing data: %e", e)
+	}
+
+	if s != len(d) {
+		t.Errorf("Imported data size mismatch: %d vs %d", s, len(d))
+	}
+}
+
+func TestImportedLoadCorrectData(t *testing.T) {
+	var (
+		f = "data/test.csv"
+		i = NewImporter()
+		s = [][]float64{
+			[]float64{0.1, 0.2, 0.3},
+			[]float64{0.4, 0.5, 0.6},
+			[]float64{0.7, 0.8, 0.9},
+		}
+	)
+
+	d, e := i.Import(f)
+	if e != nil {
+		t.Errorf("Error importing data: %e", e)
+	}
+
+	if !fsliceEqual(d, s) {
+		t.Error("Imported data mismatch")
+	}
+}
+
+func fsliceEqual(a, b [][]float64) bool {
+	if len(a) != len(b) {
+		return false
+	}
+
+	for i := 0; i < len(a); i++ {
+		if len(a[i]) != len(b[i]) {
+			return false
+		}
+
+		for j := 0; j < len(a[i]); j++ {
+			if d := math.Abs(a[i][j] - b[i][j]); d > TOLERANCE {
+				return false
+			}
+		}
+	}
+
+	return true
+}