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Highstock range approximation for a number of splines

I am trying to use Highstock to draw a 10 second ECG signal with a frequency of 250 Hz, i.e. 2500 points. I have a problem due to the approach of data grouping and the fact that in some cases each signal value can significantly differ from its neighbors, so any of the approximation functions provided by Highstock leads to a very distorted signal after drawing, because the highs and lows are lost In most cases. I created jsFiddle ( http://jsfiddle.net/YaubF/ ) showing the effect. Just drag the signal to count the groups and look at the peaks of the beats.

One solution to this problem is to use the range approximation function, which represents each group with two points (minimum and maximum), but I think that at Highstock there is currently no way to do this for rows of splines. Even if you provide your own approximation function, you will have to return one single point as a result.

I think this can be realized by providing my own approximation function, which returns min and max , and changing the function seriesProto.groupDatawhere grouping and approximation is applied to properly control this result .

Looking at the code, I really don't know how to do this.

EDIT:

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approximation: function (arr) {
    // first time or point precalculated          
    if (!gInfo || gInfo.nextPoint) {
        // first time return first value (arr[0])
        var point = gInfo ? gInfo.nextPoint : arr[0];
        // save current data to the next iteration    
        gInfo = {
            prev: arr,
            nextPoint: null
        };
        return point;
    } else {
        var prev = gInfo.prev,
            // concat current group with the previous one
            data = prev.concat(arr),
            // get min, max and their positions        
            min = Math.min.apply(null, data),
            max = Math.max.apply(null, data),
            minIdx = data.indexOf(min),
            maxIdx = data.indexOf(max),
            // order min and max
            aprox = minIdx < maxIdx ? [min, max] : [max, min];
        // save next aproximation and return current
        gInfo.nextPoint = aprox[1];
        return aprox[0];
    }
}

groupPixelWidth: .5, , .

http://jsfiddle.net/zw7D8/

0

I think you can just change the show type to isarange, where the default values ​​are the same. I updated the example:

  • change data format:

    var data = getData();

for(var i in data) {
    data[i] = [i, data[i], data[i]];   
}

  • set different types of series:

    series: [{
    type: 'arearange',
    pointInterval: 4, // 250Hz
    data: data,
    dataGrouping: {
        enabled: true
    },
    enabled: true
}]

    And a live demo: http://jsfiddle.net/xzcwB/

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