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Axibase Time Series Database - filter out negative values on time chart

I am using Axibase Time Series Database Community Edition, version 10552, to store my photovoltaic and sun altitude data. Sun altitude values are negative during the night time and I don't want to see them on my graphs.

How can I view only the positive values? Anyone know a setting or a trick that can acheive this?

Here is my current Time Chart widget configuration:

[widget]
  type = chart
  title = PV power
  timespan = 3 day
  entity = pvout.25630

[series]
  label = Sun Altitude at (-35.3089, 149.2004)
  metric = sun_altitude
  color = orange
   [tags]
    lat = -35.3089 
    lon = 149.2004

Here is a screenshot of what I am actually seeing at the moment:

enter image description here

Here is an example in Chart Lab:

https://axibase.com/chartlab/3170e35d/2/

Solution

  • Good question.

    There are several ways to hide or filter out the negative values:

    1. replace-value setting uses an expression to modify or filter series values:

      [widget]
  type = chart
  title = PV power
  timespan = 3 day
  entity = pvout.25630

[series]
  label = Sun Altitude at (-35.3089, 149.2004)
  metric = sun_altitude
  color = orange

  replace-value = value < 0 ? null : value

  [tags]
   lat=-35.3089 
   lon=149.2004

    This expression will filter out all values that are less than 0 from the series.

    Results: https://axibase.com/chartlab/3170e35d/3/

    replace-value

    1. min-range-force setting can be used to set the minimum range of the y-axis:

      [widget]
  type = chart
  title = PV power
  timespan = 3 day
  entity = pvout.25630

  min-range-force = 0

[series]
  label = Sun Altitude at (-35.3089, 149.2004)
  metric = sun_altitude
  color = orange

  [tags]
   lat=-35.3089 
   lon=149.2004

    Results: https://axibase.com/chartlab/3170e35d/4/

    enter image description here

    1. If you are using a script to calculate the Sun Altitude, then you can use the Math.max function:

      [widget]
  type = chart
  title = PV power
  timespan = 3 day

[series]
  label = Altitude
  #API: SunCalc.getPosition = function (date, lat, lng)
  value = var pos = SunCalc.getPosition(new Date(time), -35.3089, 149.2004);
  value = return Math.max(0, pos.altitude)
  frequency = 30 minute
  color = orange

    Results: https://axibase.com/chartlab/3170e35d/5/

    enter image description here

    1. value equation can be used to create a computed series, excluding the negative values:

      [widget]
  type = chart
  title = PV power
  timespan = 3 day
  entity = pvout.25630

[series]
  metric = sun_altitude
  display = false
  alias = sun_alt

 [tags]
  lat=-35.3089 
  lon=149.2004

[series]
  label = Sun Altitude at (-35.3089, 149.2004)
  value = Math.max(0, value('sun_alt'))
  color = orange

    In this case, we hide the original series and assign an alias, then we use the value = Math.max(0, value('sun_alt')) equation to create a new computed series without the negative values.

    Results: https://axibase.com/chartlab/3170e35d/6/

    enter image description here