定制函数

定制函数

eKuiper 可以定制函数，函数的开发、编译及使用请参见这里。

echo 插件

函数	示例	说明
echo	echo(avg)	原样输出参数值

echo(avg) 示例

假设 avg 类型为 int ，值为30，则结果为: [{"r1":30}]
```
SELECT echo(avg) as r1 FROM test;
```

countPlusOne 插件

函数	示例	说明
countPlusOne	countPlusOne(avg)	输出参数长度加一的值

countPlusOne(avg) 示例

假设 avg 类型为 []int ，值为[1,2,3]，则结果为: [{"r1":4}]
```
SELECT countPlusOne(avg) as r1 FROM test;
```

accumulateWordCount 插件

函数	示例	说明
accumulateWordCount	accumulateWordCount(avg,sep)	函数统计一共有多少个单词

accumulateWordCount(avg,sep) 示例

假设 avg 类型为 string ，值为My name is Bob；sep 类型为 string ，值为空格,则结果为: [{"r1":4}]
```
SELECT accumulateWordCount(avg,sep) as r1 FROM test;
```

图像处理插件

图像处理目前暂时只支持png和jpeg格式

函数	示例	说明
resize	resize(avg,width, height)	创建具有新尺寸（宽度，高度）的缩放图像。如果 width 或 height 设置为0，则将其设置为长宽比保留值
thumbnail	thumbnail(avg,maxWidth, maxHeight)	将保留宽高比的图像缩小到最大尺寸( maxWidth，maxHeight)。

resize(avg,width, height)示例

其中 avg 类型为 []byte 。

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

thumbnail(avg,maxWidth, maxHeight)示例

其中 avg 类型为 []byte。

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

Geohash 插件

函数	示例	说明
geohashEncode	geohashEncode(la,lo float64)(string)	将经纬度编码为字符串
geohashEncodeInt	geohashEncodeInt(la,lo float64)(uint64)	将经纬度编码为无类型整数
geohashDecode	geohashDecode(hash string)(la,lo float64)	将字符串解码为经纬度
geohashDecodeInt	geohashDecodeInt(hash uint64)(la,lo float64)	将无类型整数解码为经纬度
geohashBoundingBox	geohashBoundingBox(hash string)(string)	返回字符串编码的区域
geohashBoundingBoxInt	geohashBoundingBoxInt(hash uint64)(string)	返回无类型整数编码的区域
geohashNeighbor	geohashNeighbor(hash string,direction string)(string)	返回一个字符串对应方向上的邻居（方向列表：North NorthEast East SouthEast South SouthWest West NorthWest）
geohashNeighborInt	geohashNeighborInt(hash uint64,direction string)(uint64)	返回一个无类型整数对应方向上的邻居（方向列表：North NorthEast East SouthEast South SouthWest West NorthWest）
geohashNeighbors	geohashNeighbors(hash string)([]string)	返回一个字符串的所有邻居
geohashNeighborsInt	geohashNeighborsInt(hash uint64)([]uint64)	返回一个无类型整数的所有邻居

geohashEncode 示例

输入：{"lo" :131.036192,"la":-25.345457}
输出：{"geohashEncode":"qgmpvf18h86e"}

SELECT geohashEncode(la,lo) FROM test

geohashEncodeInt 示例

输入：{"lo" :131.036192,"la":-25.345457}
输出：{"geohashEncodeInt":12963433097944239317}

SELECT geohashEncodeInt(la,lo) FROM test

geohashDecode 示例

输入：{"hash" :"qgmpvf18h86e"}
输出：{"geohashDecode":{"Longitude":131.036192,"Latitude":-25.345457099999997}}

SELECT geohashDecode(hash) FROM test

geohashDecodeInt 示例

输入：{"hash" :12963433097944239317}
输出：{"geohashDecodeInt":{"Longitude":131.03618861,"Latitude":-25.345456300000002}}

SELECT geohashDecodeInt(hash) FROM test

geohashBoundingBox 示例

输入：{"hash" :"qgmpvf18h86e"}
输出：{"geohashBoundingBox":{"MinLat":-25.345457140356302,"MaxLat":-25.34545697271824,"MinLng":131.03619195520878,"MaxLng":131.0361922904849}}

SELECT geohashBoundingBox(hash) FROM test

geohashBoundingBoxInt 示例

输入：{"hash" :12963433097944239317}
输出：{"geohashBoundingBoxInt":{"MinLat":-25.345456302165985,"MaxLat":-25.34545626025647,"MinLng":131.0361886024475,"MaxLng":131.03618868626654}}

SELECT geohashBoundingBoxInt(hash) FROM test

geohashNeighbor 示例

输入：{"hash" :"qgmpvf18h86e","direction":"North"}
输出：{"geohashNeighbor":"qgmpvf18h86s"}

SELECT geohashNeighbor(hash,direction) FROM test

geohashNeighborInt 示例

输入：{"hash" :12963433097944239317,"direction":"North"}
输出：{"geohashNeighborInt":12963433097944240129}

SELECT geohashNeighborInt(hash,direction) FROM test

geohashNeighbors 示例

输入：{"hash" :12963433097944239317}
输出：{"geohashNeighbors":["qgmpvf18h86s","qgmpvf18h86u","qgmpvf18h86g","qgmpvf18h86f","qgmpvf18h86d","qgmpvf18h866","qgmpvf18h867","qgmpvf18h86k"]}

SELECT geohashNeighbors(hash) FROM test

geohashNeighborsInt 示例

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

SELECT geohashNeighborsInt(hash) FROM test

LabelImage plugin

该插件为展示使用 TensorFlowLite 模型的示例插件。此函数接收一个以 bytea 类型表示的图像的输入，输出该图像的根据 tflite 模型计算的标示。

如下 SQL 中，假设输入为 peacock.jpg 文件的二进制流，则输出为字符串 “peacock”。

SELECT labelImage(self) FROM tfdemo