node-red-contrib-statistics

This node performs statistical operations on a configurable duration of incoming events.

Configuration

Output method

This algorithm is used to calculate the output value.

Slot resolution

Time is divided into slots with a fixed duration. Incoming events are assigned to the slot which corresponds to their timestamp rounded down to slot boundaries.

Number of slots

This number of slots are available. Together with the slot resolution it determines the total duration of the floating window.

Slot method

If more than one event is received for the same slot this method is used to calculate the value of the slot.

Interpolation

If there are slots without events this algorithm is used to fill them.

• No interpolation

  Only the values of received events are used.

• Step before

  The value of the next event is repeated from the next slot of the previous event.

• Step middle

  The value of every event is repeated until the middle between this event and the next event .

• Step after

  The value of previous event is repeated until the previous slot of the next event.

• Linear

  Linear interpolation between event values.

• Cosine

  Cosine interpolation between event values.

• Cubic

  Cubic interpolation between event values.

• Catmull-Rom

  Catmull-Rom interpolation between event values.

• Hermite (low tension)

  Hermite interpolation between event values with a tension of -1.

• Hermite (normal tension)

  Hermite interpolation between event values with a tension of 0.

• Hermite (high tension)

  Hermite interpolation between event values with a tension of 1.

Fraction digits

The output value is either rounded to this number of fraction digits or output without rounding.

Update automatically

If no events are received in a certain time span updates can be triggered automatically.

• Never

  Automatic updates are disabled.

• If no events are received

  An update is triggered repeatedly until the timestamp of the last received event is older than the last slot.

Number of empty slots before update

Sets the number of slots without events before an automatic update is triggered.

Input value source

The value of an event is read from this variable.

Input timestamp source

The timestamp of an event is read from this variable.

Number output frequency

Sets how often a message is sent for the number output.

• Always

  A message is sent for every event received.

• If value has changed

  A message is only sent if the calculated output value differs from the previous one.

Number output target

The number output is written to this variable.

Object output frequency

Sets how often a message is sent for the object output.

• Always

  A message is sent for every event received.

• If value has changed

  A message is only sent if the calculated output value differs from the previous one.

• Never

  The output is disabled.

Object output target

The object output is written to this variable.

Dependencies

The node is tested with Node.js v18 and Node-RED v3. Simple Statistics is used to calculate output values.

License

The MIT License (MIT). Please see License File for more information.