MaxVRAM / node-red-contrib-statistics

A Node Red node for calculating statistics on a flow.

Node Red Statistics

Calculates statistics about input data. This is a wrapper around the Simple Statistics Node library.

Inputs

Normally, the value of an input property is saved into the data set. The input property may also contain an array of values which will be saved into the data set. If data set size is greater that 0 then the size of the data set will be limited to the number of elements specified, with the oldest elements dropped first.

When a message is received with a MQTT format topic that ends with a sub-topic that is a statistical function name, that statistic is calculated and output to the output property. For example, a message with the topic data/mean would output the mean of the data received so far. Optionally, the function name can be stripped from the topic. For statistical functions that require a parameter, the parameter is passed in using the parameter property.

Example

To get started, you can try this simple example to sum an array of random values:

1. Create an [inject] node to trigger 5 [random] nodes, and feed them into a single [group] node.
2. Configure the [group] node to use mode: manual and to create: an Array. This will combine the 5 values into a single list. e.g. [1,6,9,3,4]
3. Connect the output of the [group] into a [change] node that sets msg.topic to the name of the desired function. e.g sum
4. The join the output of the [change] node to the input of the [statistics] node. Done!

See the list below for available functions, and simply swap sum in the [change] node for your desired function.

Example flow JSON

[{"id":"8d4280c37c03c87e","type":"random","z":"6e9bd01e4dd4151c","name":"","low":1,"high":10,"inte":"true","property":"payload","x":320,"y":480,"wires":[["f9a79f6ff95fae39"]]},{"id":"8e904295ce59ee22","type":"random","z":"6e9bd01e4dd4151c","name":"","low":1,"high":10,"inte":"true","property":"payload","x":320,"y":540,"wires":[["f9a79f6ff95fae39"]]},{"id":"de285d90997217a6","type":"random","z":"6e9bd01e4dd4151c","name":"","low":1,"high":10,"inte":"true","property":"payload","x":320,"y":600,"wires":[["f9a79f6ff95fae39"]]},{"id":"e8376ba4eb785bf0","type":"random","z":"6e9bd01e4dd4151c","name":"","low":1,"high":10,"inte":"true","property":"payload","x":320,"y":660,"wires":[["f9a79f6ff95fae39"]]},{"id":"8bc54d0c1f4dbe21","type":"random","z":"6e9bd01e4dd4151c","name":"","low":1,"high":10,"inte":"true","property":"payload","x":320,"y":720,"wires":[["f9a79f6ff95fae39"]]},{"id":"f9a79f6ff95fae39","type":"join","z":"6e9bd01e4dd4151c","name":"group as array","mode":"custom","build":"array","property":"payload","propertyType":"msg","key":"topic","joiner":"\\n","joinerType":"str","accumulate":false,"timeout":"1","count":"5","reduceRight":false,"reduceExp":"","reduceInit":"","reduceInitType":"","reduceFixup":"","x":520,"y":600,"wires":[["047d451cce9ed7d8","6dd2fb91cb428b13"]]},{"id":"c0bfacd6fd65a955","type":"statistics","z":"6e9bd01e4dd4151c","name":"","dataSetSize":"5","inputField":"payload","inputFieldType":"msg","resultField":"payload","resultFieldType":"msg","parameterField":"","parameterFieldType":"msg","stripFunction":false,"resultOnly":true,"x":880,"y":600,"wires":[["f7983de9d1cf3cdf"]]},{"id":"047d451cce9ed7d8","type":"change","z":"6e9bd01e4dd4151c","name":"topic = func","rules":[{"t":"set","p":"topic","pt":"msg","to":"sum","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":710,"y":600,"wires":[["c0bfacd6fd65a955","e18cf0c8b0839c82"]]},{"id":"a106fa3c4574afcc","type":"inject","z":"6e9bd01e4dd4151c","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":140,"y":600,"wires":[["8d4280c37c03c87e","8e904295ce59ee22","de285d90997217a6","e8376ba4eb785bf0","8bc54d0c1f4dbe21"]]},{"id":"f7983de9d1cf3cdf","type":"debug","z":"6e9bd01e4dd4151c","name":"sum","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","statusVal":"","statusType":"auto","x":1030,"y":600,"wires":[]},{"id":"6dd2fb91cb428b13","type":"debug","z":"6e9bd01e4dd4151c","name":"array","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","statusVal":"","statusType":"auto","x":690,"y":520,"wires":[]},{"id":"e18cf0c8b0839c82","type":"debug","z":"6e9bd01e4dd4151c","name":"topic","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","statusVal":"","statusType":"auto","x":890,"y":660,"wires":[]}]

Functions

The functions in the Simple Statistics library that are supported are:

• bernoulliDistribution
• chunk
• ckmeans
• cumulativeStdNormalProbability
• equalIntervalBreaks
• errorFunction
• extent
• factorial
• inverseErrorFunction
• gamma
• geometricMean
• harmonicMean
• interquartileRange
• medianAbsoluteDeviation
• max
• mean
• median
• min
• mode
• poissonDistribution
• probit
• product
• quantile
• quantileRank
• rootMeanSquare
• sample
• sampleWithReplacement
• sampleKurtosis
• sampleSkewness
• sampleStandardDeviation
• shuffle
• standardDeviation
• sum
• sumNthPowerDeviations
• tTest
• uniqueCount
• variance

In addition, three other functions are implemented:

• size - returns the size of the data set
• clear - clears the data set
• dump - dumps the data set in an array

These three functions can also contain a data item or array of data items which are added to the data set before calculating the result for size or dump, or after the data set is cleared for clear.

For more detailed information about the functions see the Simple Statistics API documentation.