Custom function

eKuiper can customize functions. For the development, compilation and use of functions, please see here.

echo plugin

Function	Example	Description
echo	echo(avg)	Output parameter value as it is

echo(avg) example

• Assuming the type of avg is int and the value is 30, the result is: [{"r1":30}]

  SELECT echo(avg) as r1 FROM test;

countPlusOne plugin

Function	Example	Description
countPlusOne	countPlusOne(avg)	Output the value of the parameter length plus one

countPlusOne(avg) example

• Assuming the type of avg is []int and the value is [1,2,3], the result is: [{"r1":4}]

  SELECT countPlusOne(avg) as r1 FROM test;

accumulateWordCount plugin

Function	Example	Description
accumulateWordCount	accumulateWordCount(avg,sep)	The function counts how many words there are

accumulateWordCount(avg,sep) example

• Assuming that the avg type is string and the value is My name is Bob, the sep type is string and the value is a space, the result is: [{"r1":4}]

  SELECT accumulateWordCount(avg,sep) as r1 FROM test;

Image processing plugin

Image processing currently only supports the formats of png and jpeg

Function	Example	Description
resize	resize(avg, width, height, [isRaw])	Create a scaled image with new dimensions (width, height). If width or height is set to 0, it is set to the reserved value of aspect ratio. isRaw is optional, specifies whether to output raw data instead of encoded format like jpeg which is commonly used in AI inference.
thumbnail	thumbnail(avg,maxWidth, maxHeight)	Reduce the image that retains the aspect ratio to the maximum size (maxWidth, maxHeight).

resize(avg,width, height) example

• The avg type is []byte.

  SELECT resize(avg,width,height) as r1 FROM test;

thumbnail(avg,maxWidth, maxHeight) example

• The avg type is []byte.

  SELECT countPlusOne(avg,maxWidth, maxHeight) as r1 FROM test;

Geohash plugin

Function	Example	Description
geohashEncode	geohashEncode(la,lo float64)(string)	Encode latitude and longitude as a string
geohashEncodeInt	geohashEncodeInt(la,lo float64)(uint64)	Encode latitude and longitude as an unsigned integer
geohashDecode	geohashDecode(hash string)(la,lo float64)	Decode a string into latitude and longitude
geohashDecodeInt	geohashDecodeInt(hash uint64)(la,lo float64)	Decode an unsigned integers into latitude and longitude
geohashBoundingBox	geohashBoundingBox(hash string)(string)	Returns the area encoded by a string
geohashBoundingBoxInt	geohashBoundingBoxInt(hash uint64)(string)	Returns the area encoded by an unsigned integer
geohashNeighbor	geohashNeighbor(hash string,direction string)(string)	Returns the neighbor in the corresponding direction of a string (Direction list: North NorthEast East SouthEast South SouthWest West NorthWest)
geohashNeighborInt	geohashNeighborInt(hash uint64,direction string)(uint64)	Returns the neighbor in the corresponding direction of an unsigned integer (Direction list: North NorthEast East SouthEast South SouthWest West NorthWest)
geohashNeighbors	geohashNeighbors(hash string)([]string)	Return all neighbors of a string
geohashNeighborsInt	geohashNeighborsInt(hash uint64)([]uint64)	Return all neighbors of an unsigned integer

geohashEncode example

• Input: {"lo" :131.036192,"la":-25.345457}
• Output: {"geohashEncode":"qgmpvf18h86e"}

SELECT geohashEncode(la,lo) FROM test

geohashEncodeInt example

• Input: {"lo" :131.036192,"la":-25.345457}
• Output: {"geohashEncodeInt":12963433097944239317}

SELECT geohashEncodeInt(la,lo) FROM test

geohashDecode example

• Input: {"hash" :"qgmpvf18h86e"}
• Output: {"geohashDecode":{"Longitude":131.036192,"Latitude":-25.345457099999997}}

SELECT geohashDecode(hash) FROM test

geohashDecodeInt example

• Input: {"hash" :12963433097944239317}
• Output: {"geohashDecodeInt":{"Longitude":131.03618861,"Latitude":-25.345456300000002}}

SELECT geohashDecodeInt(hash) FROM test

geohashBoundingBox example

• Input: {"hash" :"qgmpvf18h86e"}
• Output: {"geohashBoundingBox":{"MinLat":-25.345457140356302,"MaxLat":-25.34545697271824,"MinLng":131.03619195520878,"MaxLng":131.0361922904849}}

SELECT geohashBoundingBox(hash) FROM test

geohashBoundingBoxInt example

• Input: {"hash" :12963433097944239317}
• Output: {"geohashBoundingBoxInt":{"MinLat":-25.345456302165985,"MaxLat":-25.34545626025647,"MinLng":131.0361886024475,"MaxLng":131.03618868626654}}

SELECT geohashBoundingBoxInt(hash) FROM test

geohashNeighbor example

• Input: {"hash" :"qgmpvf18h86e","direction":"North"}
• Output: {"geohashNeighbor":"qgmpvf18h86s"}

SELECT geohashNeighbor(hash,direction) FROM test

geohashNeighborInt example

• Input:{"hash" :12963433097944239317,"direction":"North"}
• Output:{"geohashNeighborInt":12963433097944240129}

SELECT geohashNeighborInt(hash,direction) FROM test

geohashNeighbors example

• Input: {"hash" :12963433097944239317}
• Output: {"geohashNeighbors":["qgmpvf18h86s","qgmpvf18h86u","qgmpvf18h86g","qgmpvf18h86f","qgmpvf18h86d","qgmpvf18h866","qgmpvf18h867","qgmpvf18h86k"]}

SELECT geohashNeighbors(hash) FROM test

geohashNeighborsInt example

• Input: {"hash" :"qgmpvf18h86e","neber":"North"}
• Output: {"geohashNeighborsInt":[12963433097944240129,12963433097944240131,12963433097944240130,12963433097944237399,12963433097944237397,12963433097944150015,12963433097944152746,12963433097944152747]}

SELECT geohashNeighborsInt(hash) FROM test

LabelImage plugin

This is a sample plugin(use in docker image tags with -slim suffix) to demonstrate the usage of TensorFlowLite(tflite) model interpreter. The function receives a bytea input representing an image and produces the AI label of the image by running the tflite model.

Assuming the input is the byte array of peacock.jpg, the output will be "peacock".

SELECT labelImage(self) FROM tfdemo

tfLite plugin

This is a plugin (use in docker image tags with -slim suffix) to do the TensorFlow Lite inference. Users just need to upload the .tflite model, call the tfLite(model_name, input_data) function in sql, then will receive results from the model inference. When uploading a model, please use the uploads interface to upload the model file. model_name should be the name for the model without .tflite suffix. Should be the key field in a message and value should be 1D array format

SELECT tfLite(model_name, input_data) FROM tfdemo