initial

1 files changed, 29 insertions, 0 deletions

diff --git a/stats.go b/stats.go
new file mode 100644
index 0000000..bc5be7c
--- /dev/null
+++ b/stats.go
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+// Provides some basic statisitcs functionality. Specifically tailored around
+// dealing with large streams of data at the moment.
+package stats
+
+import (
+	"math"
+)
+
+// Stores the average, standard deviation, and the current number of entities
+// processed
+type Stats struct {
+	Mean     float64
+	Variance float64
+	N        float64
+}
+
+// Returns the square root of 1/2 the variance, or Standard Deviation from the
+// mean
+func (s *Stats) Stdev() float64 {
+	return math.Sqrt(s.Variance / 2)
+}
+
+// Adds an entry to our struct, taking care of adjusting the Mean and Variance
+func (s *Stats) AddEntry(e float64) {
+	m := s.Mean
+	s.Mean += (e - m) / s.N
+	s.Variance += (e - m) * (e - s.Mean)
+	s.N++
+}