# Custom function

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

# echo plugin

FunctionExampleDescription
echoecho(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;
    
    1

# countPlusOne plugin

FunctionExampleDescription
countPlusOnecountPlusOne(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;
    
    1

# accumulateWordCount plugin

FunctionExampleDescription
accumulateWordCountaccumulateWordCount(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;
    
    1

# Image processing plugin

Image processing currently only supports the formats of png and jpeg

FunctionExampleDescription
resizeresize(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.
thumbnailthumbnail(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;
    
    1

thumbnail(avg,maxWidth, maxHeight) example

  • The avg type is []byte.

    SELECT countPlusOne(avg,maxWidth, maxHeight) as r1 FROM test;
    
    1

# Geohash plugin

FunctionExampleDescription
geohashEncodegeohashEncode(la,lo float64)(string)Encode latitude and longitude as a string
geohashEncodeIntgeohashEncodeInt(la,lo float64)(uint64)Encode latitude and longitude as an unsigned integer
geohashDecodegeohashDecode(hash string)(la,lo float64)Decode a string into latitude and longitude
geohashDecodeIntgeohashDecodeInt(hash uint64)(la,lo float64)Decode an unsigned integers into latitude and longitude
geohashBoundingBoxgeohashBoundingBox(hash string)(string)Returns the area encoded by a string
geohashBoundingBoxIntgeohashBoundingBoxInt(hash uint64)(string)Returns the area encoded by an unsigned integer
geohashNeighborgeohashNeighbor(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)
geohashNeighborIntgeohashNeighborInt(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)
geohashNeighborsgeohashNeighbors(hash string)([]string)Return all neighbors of a string
geohashNeighborsIntgeohashNeighborsInt(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
1

geohashEncodeInt example

  • Input: {"lo" :131.036192,"la":-25.345457}
  • Output: {"geohashEncodeInt":12963433097944239317}
SELECT geohashEncodeInt(la,lo) FROM test
1

geohashDecode example

  • Input: {"hash" :"qgmpvf18h86e"}
  • Output: {"geohashDecode":{"Longitude":131.036192,"Latitude":-25.345457099999997}}
SELECT geohashDecode(hash) FROM test
1

geohashDecodeInt example

  • Input: {"hash" :12963433097944239317}
  • Output: {"geohashDecodeInt":{"Longitude":131.03618861,"Latitude":-25.345456300000002}}
SELECT geohashDecodeInt(hash) FROM test
1

geohashBoundingBox example

  • Input: {"hash" :"qgmpvf18h86e"}
  • Output: {"geohashBoundingBox":{"MinLat":-25.345457140356302,"MaxLat":-25.34545697271824,"MinLng":131.03619195520878,"MaxLng":131.0361922904849}}
SELECT geohashBoundingBox(hash) FROM test
1

geohashBoundingBoxInt example

  • Input: {"hash" :12963433097944239317}
  • Output: {"geohashBoundingBoxInt":{"MinLat":-25.345456302165985,"MaxLat":-25.34545626025647,"MinLng":131.0361886024475,"MaxLng":131.03618868626654}}
SELECT geohashBoundingBoxInt(hash) FROM test
1

geohashNeighbor example

  • Input: {"hash" :"qgmpvf18h86e","direction":"North"}
  • Output: {"geohashNeighbor":"qgmpvf18h86s"}
SELECT geohashNeighbor(hash,direction) FROM test
1

geohashNeighborInt example

  • Input:{"hash" :12963433097944239317,"direction":"North"}
  • Output:{"geohashNeighborInt":12963433097944240129}
SELECT geohashNeighborInt(hash,direction) FROM test
1

geohashNeighbors example

  • Input: {"hash" :12963433097944239317}
  • Output: {"geohashNeighbors":["qgmpvf18h86s","qgmpvf18h86u","qgmpvf18h86g","qgmpvf18h86f","qgmpvf18h86d","qgmpvf18h866","qgmpvf18h867","qgmpvf18h86k"]}
SELECT geohashNeighbors(hash) FROM test
1

geohashNeighborsInt example

  • Input: {"hash" :"qgmpvf18h86e","neber":"North"}
  • Output: {"geohashNeighborsInt":[12963433097944240129,12963433097944240131,12963433097944240130,12963433097944237399,12963433097944237397,12963433097944150015,12963433097944152746,12963433097944152747]}
SELECT geohashNeighborsInt(hash) FROM test
1

# LabelImage plugin

This is a sample plugin to demonstrate the usage of TensorFlowLite(tflite) model interpreter. The function receives a bytea input representing an image and produce 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
1