user149667

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• How save average and standard deviation of data stream everyone minute in the csv

  @user149667 started

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  @Gordon replied
• How save average and standard deviation of data stream everyone minute in the csv

  in Bangle.js • 1 year, 7 months

  

  Lol I just realised hehe.

• How save average and standard deviation of data stream everyone minute in the csv

  in Bangle.js • 1 year, 7 months

  

  Thank you very much @Gordon
  I am using BangleJs2. I will use the arraybuffer and share the code very soon.
  Thanks again.

• How save average and standard deviation of data stream everyone minute in the csv

  in Bangle.js • 1 year, 7 months

  

  New to both Bangle and JavaScript.
  I am currently trying to save all the HRM, accelerometer and magnetometer output's individual average and standard deviation once in minute. The code below is giving me Interpreter error: LOW_MEMORY.

  Please help.

  Bangle.setCompassPower(1);
  filename = "trolololo.csv";
  
  var allData = require("Storage").open(filename, "a");
  Bangle.setHRMPower(1);
  
  const buffer = {
    start: null,
    end: null,
    data: []
  };
  const maxSamples = 100;
  
  const computeBufferAverage = () => {
    let sum = [], sum2 = [], mean = [], std = [];
    const nrows = maxSamples;
    const ncols = buffer.data[0].length;
    for(let i=0;i<ncols;i++) {
      sum[i] = 0;
      sum2[i] = 0;
      mean[i] = 0;
      std[i] = 0;
    }
  
    for (const data of buffer.data) {
      for (let i=0; i<ncols; i++) {
        sum[i] += data[i];
        sum2[i] += data[i]*data[i];
      }
    }
  
    for (let i=0; i<ncols; i++) {
      mean[i] = sum[i] / nrows;
      std[i] = Math.sqrt(nrows*sum2[i] - Math.pow(sum[i], 2))/(nrows-1);
    }
  
    return {mean: mean, std: std};
  };
  
  Bangle.on('HRM-raw', function(hrm) {
      const hrmRaw = [
        "HRM:",
        hrm.raw,
        hrm.filt,
        hrm.bpm,
        hrm.confidence
      ];
    const compass = Bangle.getCompass();
    const accel = Bangle.getAccel();
  
    if (buffer.data.length === 0) {
      buffer.start = Math.floor(Date.now());
    }
    if (buffer.data.length < maxSamples) {
      buffer.data.push([
        a.x, a.y,a.z,c.x,c.y,c.z,c.dx,c.dy,c.dz,hrm.r­aw,hrm.filt,hrm.bpm,hrm.confidence
      ]);
    } else {
      buffer.end = Math.floor(Date.now());
  
      const result = computeBufferAverage();
      const str = [
        buffer.start,
        buffer.end,
        result.mean.join(","),
        result.std.join(",")
      ].join(",");
      print(str+"\n");
      allData.write(str);
      allData.write("\n");
      buffer.data.length = 0;
    }
  
  });