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  1. Tooltip data interpolation

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    9 comments  ·  Highcharts Javascript API  ·  Admin →
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    Martin Thillerup commented  · 

    Hi Torstein,

    This was exactly what I was looking for. Had to make sure that stepped lines didn't get interpolated but other than that I could pretty much just copy the example.

    One last issue is that the interpolation values snaps to nearest value, so for a long time period without values you won't get any updated values in the tooltip. I am considering making a single transparent serie with evenly spaced values that will trigger the interpolation.

    I made a short video to demonstrate how big a difference the interpolated values makes in our use case when reading values of the chart: https://youtu.be/VFJB3_XmqYs

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    Martin Thillerup commented  · 

    Hi Torstein,
    This is something I would really like, so great news that you are revieweing this idea :)
    I have tried you hack, but for more complex datasets it does not work: http://jsfiddle.net/h0yLfL1u/
    Between 2-4 I don't get proper values.

    I am using Highcharts to show values from a process control historian. Because of the applied compression the data points are very unevenly spaced, e.g. one data point could log every 2-5 seconds and another could log every 3-8 minutes, and certainly not at the same times. The time period displayed on the chart ranges from minutes to days, so I would propably adjust the resolution dynamically to something like an interpolated value per pixel, for best performance.

    I think that with a better interpolation calculation the hack could work, but a native feature is preferred :)

    An idea, but I don't know what is possible: If it is possible to get the data series values before and after the position of the crosshair you could do the interpolation in the tooltip instead of adding interpolated data series to the chart.

    Martin Thillerup supported this idea  ·