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// Copyright 2015 The LUCI Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package distribution contains distribution metrics, fixed width and geometric
// bucketers.
package distribution
// A Distribution holds a statistical summary of a collection of floating-point
// values.
type Distribution struct {
b *Bucketer
buckets []int64
count int64
sum float64
lastNonZeroBucket int
}
// New creates a new distribution using the given bucketer. Passing a nil
// Bucketer will use DefaultBucketer.
func New(b *Bucketer) *Distribution {
if b == nil {
b = DefaultBucketer
}
return &Distribution{b: b, lastNonZeroBucket: -1}
}
// Add adds the sample to the distribution and updates the statistics.
func (d *Distribution) Add(sample float64) {
i := d.b.Bucket(sample)
if i >= len(d.buckets) {
d.buckets = append(d.buckets, make([]int64, i-len(d.buckets)+1)...)
}
d.buckets[i]++
d.sum += sample
d.count++
if i > d.lastNonZeroBucket {
d.lastNonZeroBucket = i
}
}
// Bucketer returns the bucketer used in this distribution.
func (d *Distribution) Bucketer() *Bucketer { return d.b }
// Buckets provides access to the underlying buckets slice. len(Buckets) will
// be <= Bucketer().NumBuckets()
func (d *Distribution) Buckets() []int64 { return d.buckets }
// Count returns the number of times Add has been called.
func (d *Distribution) Count() int64 { return d.count }
// Sum returns the sum of all samples passed to Add.
func (d *Distribution) Sum() float64 { return d.sum }
// LastNonZeroBucket returns the index into Buckets() of the last bucket that
// is set (non-zero). Returns -1 if Count() == 0.
func (d *Distribution) LastNonZeroBucket() int { return d.lastNonZeroBucket }