fakeData.js

var crypto = require('crypto');

//varies from -1 t0 1
var pow2_31 = Math.pow(2,31);
var randNum = function(t,seed) {
  var shasum = crypto.createHash('sha1');
  return shasum.update(""+seed+t).digest().readUInt32LE(0)/pow2_31-1;
}

var randNumGenMaker = function(seed) {
  if(typeof seed === "undefined") {seed = ''}
  seed += '';

  
  //this can be changed to change to affect the "texture" of the random data.
  var factors = [1/33,1/32,1/31,1/30,1/29,1/28,1/27,1/26,1/25,1/24,1/23,1/22,1/21,1/20,1/19,1/18,1/17,1/16,1/15,1/14,1/13,1/12,1/11,1/10,1/9,1/8,1/7,1/6,1/5,1/4,1/3,1/2,1/1]
 
  var power = 32;
  var startX = 0;
  var endX = Math.pow(2,power);
  var midX =  Math.pow(2,power-1);
  var startY = randNum(startX,seed)*factors[power];
  var endY = randNum(endX,seed)*factors[power];
  var midY = (endY-startY)/2+randNum(midX,seed)*factors[power-1];
  
  var helper = {
    power:power,
    startX:startX,
    endX:endX,
    midX:midX,
    startY:startY,
    endY:endY,
    midY:midY,
    aboveHelper:null,
    shrinkLeft:function() {
      var power = this.power-1;
      var startX = this.startX;
      var endX = this.midX;
      var midX =  startX+Math.pow(2,power-1);
      var startY = this.startY;
      var endY = this.midY;
      //midY= the midpoint between the start and end Y + some perturbation
      var midY = (endY+startY)/2+randNum(midX,seed)*factors[power-1];
      console.log("\tstartX="+ startX +" midX="+ midX +" endX="+ endX);
      console.log("\tstartY="+ startY +" midY="+ midY +" endY="+ endY);
      console.log("\tmidY="+(endY+startY)/2+"+randNum("+midX+",'"+seed+"')*"+factors[power-1]);
      var helper = {
        power:power,
        startX:startX,
        endX:endX,
        midX:midX,
        startY:startY,
        endY:endY,
        midY:midY,
        aboveHelper:this,
        shrinkLeft:this.shrinkLeft,
        shrinkRight:this.shrinkRight
      }
      return helper
    },
    shrinkRight:function() {
      var power = this.power-1;
      var startX = this.midX;
      var endX = this.endX;
      var midX =  startX+Math.pow(2,power-1);
      var startY = this.midY;
      var endY = this.endY;
      //midY= the midpoint between the start and end Y + some perturbation
      var midY = (endY+startY)/2+randNum(midX,seed)*factors[power-1];
      console.log("\tstartX="+ startX +" midX="+ midX +" endX="+ endX);
      console.log("\tstartY="+ startY +" midY="+ midY +" endY="+ endY);
      console.log("\tmidY="+(endY+startY)/2+"+randNum("+midX+",'"+seed+"')*"+factors[power-1]);
      var helper = {
        power:power,
        startX:startX,
        endX:endX,
        midX:midX,
        startY:startY,
        endY:endY,
        midY:midY,
        aboveHelper:this,
        shrinkLeft:this.shrinkLeft,
        shrinkRight:this.shrinkRight
      }
      return helper
    }
  }

   /////////
   ////THIS WAS REALLY HELPFUL IN DEBUGGING THE HELPER
   //h=helper
   //console.log("Making hL")
   //hL=h.shrinkLeft()
   //console.log("Making hR")
   //hR=h.shrinkRight()
   //console.log("Making hLL")
   //hLL=hL.shrinkLeft()
   //console.log("Making hLR")
   //hLR=hL.shrinkRight()
   //console.log("Making hRL")
   //hRL=hR.shrinkLeft()
   //console.log("Making hRR")
   //hRR=hR.shrinkRight()
   //if(hL.endX!=hR.startX) {
   //  console.log("1X")
   //}
   //if(hLL.endX!=hLR.startX) {
   //  console.log("2LX")
   //}
   //if(hLR.endX!=hRL.startX) {
   //  console.log("2MX")
   //}
   //if(hRL.endX!=hRR.startX) {
   //  console.log("2RX")
   //}
   //if(hL.endY!=hR.startY) {
   //  console.log("1Y")
   //}
   //if(hLL.endY!=hLR.startY) {
   //  console.log("2LY")
   //}
   //if(hLR.endY!=hRL.startY) {
   //  console.log("2MY")
   //}
   //if(hRL.endY!=hRR.startY) {
   //  console.log("2RY")
   //}

  var randNumGen = function(x) {
    while(true) {
    console.log("at ["+ helper.startX +","+ helper.endX +"]")
    if(x==helper.startX) {
      console.log("  at "+ helper.startX +" found "+ helper.startY)
      return helper.startY
    } else if(x>helper.startX && x<helper.midX) {
      console.log("  shrinking left")
      helper = helper.shrinkLeft()
    } else if(x>=helper.midX && x<helper.endX) {
      console.log("  shrinking right")
      helper = helper.shrinkRight()
    } else {
      console.log("  growing")
      helper = helper.aboveHelper
    }
    }
  }

  return randNumGen;
}

var seriesGenerator = function(start,end,delta,seed) {
  if(typeof delta === "undefined") {
    delta = 1
  }
  if(typeof seed === "undefined") {seed = ''}
  seed += '';
  var randNumGen = randNumGenMaker(seed);
  var series = []
  for(var t=start; t<end ; t += delta) {
    series.push(randNumGen(t))
  }
  return series;
}

module.exports.seriesGenerator = seriesGenerator