Upstream montanaflynn/stats state of the touched files before 9ead4dd879

quartile.go

@@ -0,0 +1,74 @@
+package stats
+
+import "math"
+
+// Quartiles holds the three quartile points
+type Quartiles struct {
+	Q1 float64
+	Q2 float64
+	Q3 float64
+}
+
+// Quartile returns the three quartile points from a slice of data
+func Quartile(input Float64Data) (Quartiles, error) {
+
+	il := input.Len()
+	if il == 0 {
+		return Quartiles{}, EmptyInputErr
+	}
+
+	// Start by sorting a copy of the slice
+	copy := sortedCopy(input)
+
+	// Find the cutoff places depeding on if
+	// the input slice length is even or odd
+	var c1 int
+	var c2 int
+	if il%2 == 0 {
+		c1 = il / 2
+		c2 = il / 2
+	} else {
+		c1 = (il - 1) / 2
+		c2 = c1 + 1
+	}
+
+	// Find the Medians with the cutoff points
+	Q1, _ := Median(copy[:c1])
+	Q2, _ := Median(copy)
+	Q3, _ := Median(copy[c2:])
+
+	return Quartiles{Q1, Q2, Q3}, nil
+
+}
+
+// InterQuartileRange finds the range between Q1 and Q3
+func InterQuartileRange(input Float64Data) (float64, error) {
+	if input.Len() == 0 {
+		return math.NaN(), EmptyInputErr
+	}
+	qs, _ := Quartile(input)
+	iqr := qs.Q3 - qs.Q1
+	return iqr, nil
+}
+
+// Midhinge finds the average of the first and third quartiles
+func Midhinge(input Float64Data) (float64, error) {
+	if input.Len() == 0 {
+		return math.NaN(), EmptyInputErr
+	}
+	qs, _ := Quartile(input)
+	mh := (qs.Q1 + qs.Q3) / 2
+	return mh, nil
+}
+
+// Trimean finds the average of the median and the midhinge
+func Trimean(input Float64Data) (float64, error) {
+	if input.Len() == 0 {
+		return math.NaN(), EmptyInputErr
+	}
+
+	c := sortedCopy(input)
+	q, _ := Quartile(c)
+
+	return (q.Q1 + (q.Q2 * 2) + q.Q3) / 4, nil
+}

quartile_test.go

@@ -0,0 +1,84 @@
+package stats_test
+
+import (
+	"testing"
+
+	"github.com/montanaflynn/stats"
+)
+
+func TestQuartile(t *testing.T) {
+	s1 := []float64{6, 7, 15, 36, 39, 40, 41, 42, 43, 47, 49}
+	s2 := []float64{7, 15, 36, 39, 40, 41}
+
+	for _, c := range []struct {
+		in []float64
+		Q1 float64
+		Q2 float64
+		Q3 float64
+	}{
+		{s1, 15, 40, 43},
+		{s2, 15, 37.5, 40},
+	} {
+		quartiles, err := stats.Quartile(c.in)
+		if err != nil {
+			t.Errorf("Should not have returned an error")
+		}
+
+		if quartiles.Q1 != c.Q1 {
+			t.Errorf("Q1 %v != %v", quartiles.Q1, c.Q1)
+		}
+		if quartiles.Q2 != c.Q2 {
+			t.Errorf("Q2 %v != %v", quartiles.Q2, c.Q2)
+		}
+		if quartiles.Q3 != c.Q3 {
+			t.Errorf("Q3 %v != %v", quartiles.Q3, c.Q3)
+		}
+	}
+
+	_, err := stats.Quartile([]float64{})
+	if err == nil {
+		t.Errorf("Empty slice should have returned an error")
+	}
+}
+
+func TestInterQuartileRange(t *testing.T) {
+	s1 := []float64{102, 104, 105, 107, 108, 109, 110, 112, 115, 116, 118}
+	iqr, _ := stats.InterQuartileRange(s1)
+
+	if iqr != 10 {
+		t.Errorf("IQR %v != 10", iqr)
+	}
+
+	_, err := stats.InterQuartileRange([]float64{})
+	if err == nil {
+		t.Errorf("Empty slice should have returned an error")
+	}
+}
+
+func TestMidhinge(t *testing.T) {
+	s1 := []float64{1, 3, 4, 4, 6, 6, 6, 6, 7, 7, 7, 8, 8, 9, 9, 10, 11, 12, 13}
+	mh, _ := stats.Midhinge(s1)
+
+	if mh != 7.5 {
+		t.Errorf("Midhinge %v != 7.5", mh)
+	}
+
+	_, err := stats.Midhinge([]float64{})
+	if err == nil {
+		t.Errorf("Empty slice should have returned an error")
+	}
+}
+
+func TestTrimean(t *testing.T) {
+	s1 := []float64{1, 3, 4, 4, 6, 6, 6, 6, 7, 7, 7, 8, 8, 9, 9, 10, 11, 12, 13}
+	tr, _ := stats.Trimean(s1)
+
+	if tr != 7.25 {
+		t.Errorf("Trimean %v != 7.25", tr)
+	}
+
+	_, err := stats.Trimean([]float64{})
+	if err == nil {
+		t.Errorf("Empty slice should have returned an error")
+	}
+}