旋转门压缩算法(SDT)的Go实现

Posted 2022-05-10 bkzy

原理

实质上，是计算门轴到新数据点之间线段的斜率，门轴既是线段的零点。由于直线段的公式为：

x = kt+b //k为斜率,b为0点,t为时间轴,x为数据大小

上下门轴点的计算方法为：

ub=x0+ΔE //上门轴，x0为存储点的数值
db=x0-ΔE //下门轴，x0为存储点的数值

上下门斜率的计算方法为：

uk=(xt-ub)/Δt //上门斜率
dk=(xt-db)/Δt //下门斜率

在t0点，门关闭，上门斜率无线小，下门斜率无限大。随着时间轴的右伸，上门斜率逐渐变大(单向，只能变大)，下门斜率逐渐变小(单向,只能变小)。当上门斜率大于等于下门斜率时，保存前一个数据点。
具体流程为：

算法的实现

package models

import (
	"time"
)

//旋转门压缩结构体
type SdtDoor struct 
	DeltaE         float64   //门初始宽度
	LastHisV       float64   //上一次存储的数据值
	LastHisT       time.Time //上一次存储的数据时间戳
	LastRealV      float64   //上一次的实时数据值
	LastRealT      time.Time //上一次实时数据的时间戳
	MaxIntervalSec int64     //数据存储最大间隔秒数
	isinit         bool      //初始化状态
	closed         bool      //初始关门状态
	uk             float64   //上斜率
	dk             float64   //下斜率
	ub             float64   //上零点
	db             float64   //下零点


//新建旋转门压缩实体
func NewSdtDoor(deltaE float64, maxsec int64) *SdtDoor 
	sdt := &SdtDoorDeltaE: deltaE, MaxIntervalSec: maxsec, closed: true, isinit: true
	return sdt


//旋转门过滤器
func (sdt *SdtDoor) Filter(pointV float64, pointT time.Time) bool 
	if sdt.DeltaE == 0  //门宽度为零
		return true //保存每一个数据
	
	save := false   //过滤检查结果
	if sdt.isinit  //初始化状态
		sdt.isinit = false
		save = true
	 else 
		deltaT := float64(pointT.Sub(sdt.LastHisT).Milliseconds())
		//fmt.Printf("时间差:%fms\\n", deltaT)
		if sdt.closed  //开门第一个点
			if deltaT > 0 
				sdt.closed = false
				sdt.uk = (pointV - sdt.ub) / deltaT
				sdt.dk = (pointV - sdt.db) / deltaT
			
		 else 
			uk := (pointV - sdt.ub) / deltaT
			dk := (pointV - sdt.db) / deltaT
			if uk > sdt.uk  //上斜率只保存增大的
				sdt.uk = uk
			
			if dk < sdt.dk  //下斜率只保存减小的
				sdt.dk = dk
			
			if sdt.dk <= sdt.uk  //下斜率小于等于上斜率,触发保存
				save = true
			
			if !save 
				if deltaT/1000.0 > float64(sdt.MaxIntervalSec)  //已经长时间没有触发保存
					save = true
				
			

		
	
	if save 
		sdt.LastHisV = sdt.LastRealV
		sdt.LastHisT = sdt.LastRealT
		sdt.ub = sdt.LastHisV + sdt.DeltaE
		sdt.db = sdt.LastHisV - sdt.DeltaE
		sdt.closed = true
	
	sdt.LastRealV = pointV
	sdt.LastRealT = pointT
	return save

测试用例

func TestSdt(t *testing.T) 
	deltaE := 0.005 //门宽,即压缩精度
	datas := []struct 
		tstamp int64   //时间戳,UNIX秒
		sinv   float64 //正玄波值
	
		1651800000, 0,
		1651800001, 0.0998334166468282,
		1651800002, 0.198669330795061,
		1651800003, 0.29552020666134,
		1651800004, 0.389418342308651,
		1651800005, 0.479425538604203,
		1651800006, 0.564642473395035,
		1651800007, 0.644217687237691,
		1651800008, 0.717356090899523,
		1651800009, 0.783326909627483,
		1651800010, 0.841470984807897,
		1651800011, 0.891207360061435,
		1651800012, 0.932039085967226,
		1651800013, 0.963558185417193,
		1651800014, 0.98544972998846,
		1651800015, 0.997494986604054,
		1651800016, 0.999573603041505,
		1651800017, 0.991664810452469,
		1651800018, 0.973847630878195,
		1651800019, 0.946300087687414,
		1651800020, 0.909297426825682,
		1651800021, 0.863209366648874,
		1651800022, 0.80849640381959,
		1651800023, 0.74570521217672,
		1651800024, 0.675463180551151,
		1651800025, 0.598472144103956,
		1651800026, 0.515501371821464,
		1651800027, 0.427379880233829,
		1651800028, 0.334988150155904,
		1651800029, 0.239249329213982,
		1651800030, 0.141120008059866,
		1651800031, 0.0415806624332896,
		1651800032, -0.058374143427581,
		1651800033, -0.15774569414325,
		1651800034, -0.255541102026833,
		1651800035, -0.350783227689621,
		1651800036, -0.442520443294854,
		1651800037, -0.529836140908495,
		1651800038, -0.61185789094272,
		1651800039, -0.687766159183975,
		1651800040, -0.756802495307929,
		1651800041, -0.818277111064411,
		1651800042, -0.871575772413589,
		1651800043, -0.916165936749456,
		1651800044, -0.951602073889517,
		1651800045, -0.977530117665097,
		1651800046, -0.993691003633465,
		1651800047, -0.999923257564101,
		1651800048, -0.99616460883584,
		1651800049, -0.982452612624332,
		1651800050, -0.958924274663138,
		1651800051, -0.925814682327731,
		1651800052, -0.883454655720152,
		1651800053, -0.8322674422239,
		1651800054, -0.772764487555985,
		1651800055, -0.705540325570389,
		1651800056, -0.631266637872319,
		1651800057, -0.550685542597635,
		1651800058, -0.464602179413754,
		1651800059, -0.373876664830233,
		1651800060, -0.279415498198922,
		1651800061, -0.182162504272092,
		1651800062, -0.0830894028174929,
		1651800063, 0.0168139004843542,
		1651800064, 0.116549204850497,
		1651800065, 0.215119988087819,
		1651800066, 0.311541363513382,
		1651800067, 0.404849920616602,
		1651800068, 0.494113351138612,
		1651800069, 0.578439764388203,
		1651800070, 0.656986598718792,
		1651800071, 0.72896904012588,
		1651800072, 0.793667863849156,
		1651800073, 0.850436620628567,
		1651800074, 0.898708095811629,
		1651800075, 0.937999976774741,
		1651800076, 0.967919672031488,
		1651800077, 0.988168233877001,
		1651800078, 0.998543345374605,
		1651800079, 0.998941341839772,
		1651800080, 0.989358246623381,
		1651800081, 0.969889810845085,
		1651800082, 0.940730556679771,
		1651800083, 0.902171833756291,
		1651800084, 0.854598908088278,
		1651800085, 0.798487112623487,
		1651800086, 0.73439709787411,
		1651800087, 0.662969230082178,
		1651800088, 0.584917192891757,
		1651800089, 0.50102085645788,
		1651800090, 0.412118485241752,
		1651800091, 0.319098362349347,
		1651800092, 0.222889914100242,
		1651800093, 0.124454423507058,
		1651800094, 0.0247754254533542,
	
	sdt := NewSdtDoor(deltaE, 100)
	for i, dt := range datas 
		t := time.Unix(dt.tstamp, 0)
		save := sdt.Filter(dt.sinv, t)
		//fmt.Printf("%d uk=%f,dk=%f,diff=%f,save=%t\\n", i, sdt.uk, sdt.dk, sdt.uk-sdt.dk, save)
		if save 
			if i == 0 
				fmt.Println(dt)
			 else 
				if i != 1  //第一个数前面已经输出过了，不再重复
					fmt.Println(datas[i-1])
				
			
		
	

测试结果

1651800000 0
1651800001 0.0998334166468282
1651800005 0.479425538604203
1651800008 0.717356090899523
1651800011 0.891207360061435
1651800013 0.963558185417193
1651800015 0.997494986604054
1651800017 0.991664810452469
1651800019 0.946300087687414
1651800021 0.863209366648874
1651800024 0.675463180551151
1651800027 0.427379880233829
1651800032 -0.058374143427581
1651800036 -0.442520443294854
1651800039 -0.687766159183975
1651800042 -0.871575772413589
1651800044 -0.951602073889517
1651800046 -0.993691003633465
1651800048 -0.99616460883584
1651800050 -0.958924274663138
1651800052 -0.883454655720152
1651800055 -0.705540325570389
1651800058 -0.464602179413754
1651800062 -0.0830894028174929
1651800067 0.404849920616602
1651800070 0.656986598718792
1651800073 0.850436620628567
1651800075 0.937999976774741
1651800077 0.988168233877001
1651800079 0.998941341839772
1651800081 0.969889810845085
1651800083 0.902171833756291
1651800086 0.73439709787411
1651800089 0.50102085645788
1651800093 0.124454423507058

对上述测试数据绘图

参考文献

SDT旋转门压缩算法MFC图形测试
数据压缩算法：旋转门算法（SDT）的C#实现