From f6809a20e691c1dab0d0a74ea1d7d16f64eb6620 Mon Sep 17 00:00:00 2001
From: "didier.amyot" <didier.amyot@gmail.com>
Date: Tue, 13 May 2014 20:59:51 -0400
Subject: [PATCH] started the stats module

---
 stats.go      | 41 +++++++++++++++++++++++++++++++++++++++++
 stats_test.go | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 76 insertions(+)
 create mode 100644 stats.go
 create mode 100644 stats_test.go

diff --git a/stats.go b/stats.go
new file mode 100644
index 0000000..b90f015
--- /dev/null
+++ b/stats.go
@@ -0,0 +1,41 @@
+package main
+
+import (
+	"fmt"
+)
+
+var _ = fmt.Print
+
+const initialLength int = 1024
+const verySmall float64 = -100000
+const veryBig float64 = 100000
+
+type StatAggregator struct {
+	sum             float64
+	sumOfTheSquares float64
+	n               int
+	histogram       []float64
+	min             float64
+	max             float64
+}
+
+type Stats struct{}
+
+func NewStatAggregator() *StatAggregator {
+	return &StatAggregator{0, 0, 0, make([]float64, initialLength), veryBig, verySmall}
+}
+
+func (this *StatAggregator) AddStats(dataChannel chan float64, output chan *Stats) {
+	for datum := range dataChannel {
+		this.sum += datum
+		this.sumOfTheSquares += datum * datum
+		this.n += 1
+		if datum < this.min {
+			this.min = datum
+		}
+		if datum > this.max {
+			this.max = datum
+		}
+	}
+	output <- nil
+}
diff --git a/stats_test.go b/stats_test.go
new file mode 100644
index 0000000..c10951e
--- /dev/null
+++ b/stats_test.go
@@ -0,0 +1,35 @@
+package main
+
+import (
+	"testing"
+)
+
+func TestNewStats(t *testing.T) {
+	s := NewStatAggregator()
+	if s.n != 0 ||
+		s.sum != 0 ||
+		s.sumOfTheSquares != 0 ||
+		len(s.histogram) != initialLength ||
+		s.min != veryBig ||
+		s.max != verySmall {
+		t.Fail()
+	}
+}
+
+func TestAddStatsBasic(t *testing.T) {
+
+	numbers := []float64{-1, 1, 20, 3}
+	c := make(chan float64)
+	o := make(chan *Stats)
+	s := NewStatAggregator()
+	go s.AddStats(c, o)
+	for _, n := range numbers {
+		c <- n
+	}
+	close(c)
+	<-o
+	if s.n != 4. || s.min != -1. || s.max != 20. || s.sum != 23. || s.sumOfTheSquares != 411. {
+		t.Error(">>>", s.max, s.min)
+	}
+
+}