| // Copyright 2010 Petar Maymounkov. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package llrb |
| |
| import "math" |
| |
| // avgVar maintains the average and variance of a stream of numbers |
| // in a space-efficient manner. |
| type avgVar struct { |
| count int64 |
| sum, sumsq float64 |
| } |
| |
| func (av *avgVar) Init() { |
| av.count = 0 |
| av.sum = 0.0 |
| av.sumsq = 0.0 |
| } |
| |
| func (av *avgVar) Add(sample float64) { |
| av.count++ |
| av.sum += sample |
| av.sumsq += sample * sample |
| } |
| |
| func (av *avgVar) GetCount() int64 { return av.count } |
| |
| func (av *avgVar) GetAvg() float64 { return av.sum / float64(av.count) } |
| |
| func (av *avgVar) GetTotal() float64 { return av.sum } |
| |
| func (av *avgVar) GetVar() float64 { |
| a := av.GetAvg() |
| return av.sumsq/float64(av.count) - a*a |
| } |
| |
| func (av *avgVar) GetStdDev() float64 { return math.Sqrt(av.GetVar()) } |
