如何通过数组[序列[字符串]到Apache的火花UDF? (错误:不适用) [英] How to pass Array[Seq[String]] to apache spark udf? (Error: Not Applicable)
问题描述
我在阶下的Apache火花UDF:
VAL myFunc的UDF = {
(userBias:浮动,otherBiases:地图[长,浮法]
userFactors:序号[浮点],语境:序号[字符串])=>
VAR的结果=的Float.NaN 如果(userFactors!= NULL){
VAR contexBias = 0F 对于(CC< - 上下文){
contexBias + = otherBiases(contextMapping(CC))
} //结果的定义
// ...
}
结果
}
现在我想传递参数给这个函数,但是我总是得到的消息不适用由于参数背景
。我知道,用户自定义函数按行采取的投入,这个功能如果我删除运行背景
...如何解决这个问题?为什么它不读阵行[SEQ [字符串]
,即从背景
?或者,也可以接受通过背景
为数据帧
或类似的东西。
//背景是数组[序列[字符串]
VAL一个= sc.parallelize(序列((1,2),(3,4)))。toDF(一,B)
VAL上下文= a.collect.map(_。toSeq.map(_。的toString))// userBias(偏见),otherBias(偏见),并userFactors(特征)
//有一个类型列,而userBias ...是DataFrames
myDataframe.select(数据集(*),
myFunc的(userBias(偏见),
otherBias(偏置),
userFactors(特征),
上下文)
。至于($(NEWCOL)))
更新:
我试过的答案显示的解决方案 zero323
,但是仍然有一个小问题与背景:数组[序列[字符串]
。特别是,问题是循环于此Array 为(CC< - 上下文){contexBias + = otherBiases(contextMapping(CC))}
。我要传递一个字符串 contextMapping
,而不是序列[字符串]
:
高清myFunc的(背景:数组[序号[字符串]])= {UDF
(userBias:浮动,otherBiases:地图[长,浮法]
userFactors:序号[浮点])=>
VAR的结果=的Float.NaN 如果(userFactors!= NULL){
VAR contexBias = 0F
对于(CC< - 上下文){
contexBias + = otherBiases(contextMapping(CC))
} //结果估计 }
结果
}
现在我把它叫做如下:
myDataframe.select(数据集(*),
myFunc的(上下文)(userBias(偏见),
otherBias(偏置),
userFactors(特征))
。至于($(NEWCOL)))
这是直接传递给UDF的任何参数必须是一个列
,所以如果你想传递常量数组你必须把它转换为文字列:
进口org.apache.spark.sql.functions {阵列,点燃}VAL myFunc的:org.apache.spark.sql.UserDefinedFunction =?myFunc的(
userBias(偏见),
otherBias(偏置),
userFactors(特征),
// org.apache.spark.sql.Column
阵列(context.map(XS =>阵列(xs.map(亮_):_ *)):_ *)
)
非 - 列
对象只能间接地通过封闭传递,例如像这样的:
高清myFunc的(背景:数组[序号[字符串]])= {UDF
(userBias:浮动,otherBiases:地图[长,浮点型],userFactors:序号[浮点])=>
???
}myFunc的(上下文)(userBias(偏见),otherBias(偏见),userFactors(特征))
I have the following apache spark udf in scala:
val myFunc = udf {
(userBias: Float, otherBiases: Map[Long, Float],
userFactors: Seq[Float], context: Seq[String]) =>
var result = Float.NaN
if (userFactors != null) {
var contexBias = 0f
for (cc <- context) {
contexBias += otherBiases(contextMapping(cc))
}
// definition of result
// ...
}
result
}
Now I want to pass parameters to this function, however I always get the message Not Applicable due to the parameter context
. I know that user defined functions take inputs by rows, and this function runs if I delete context
... How to solve this issue? Why doesn't it read rows from Array[Seq[String]]
, i.e. from context
? Alternatively, it would be acceptable to passcontext
as DataFrame
or something similar.
// context is Array[Seq[String]]
val a = sc.parallelize(Seq((1,2),(3,4))).toDF("a", "b")
val context = a.collect.map(_.toSeq.map(_.toString))
// userBias("bias"), otherBias("biases") and userFactors("features")
// have a type Column, while userBias... are DataFrames
myDataframe.select(dataset("*"),
myFunc(userBias("bias"),
otherBias("biases"),
userFactors("features"),
context)
.as($(newCol)))
UPDATE:
I tried the solution indicated in the answer of zero323
, however still there is a small issue with context: Array[Seq[String]]
. In particular the problem is with looping over this Array for (cc <- context) { contexBias += otherBiases(contextMapping(cc)) }
. I should pass a String to contextMapping
, not a Seq[String]
:
def myFunc(context: Array[Seq[String]]) = udf {
(userBias: Float, otherBiases: Map[Long, Float],
userFactors: Seq[Float]) =>
var result = Float.NaN
if (userFactors != null) {
var contexBias = 0f
for (cc <- context) {
contexBias += otherBiases(contextMapping(cc))
}
// estimation of result
}
result
}
Now I call it as follows:
myDataframe.select(dataset("*"),
myFunc(context)(userBias("bias"),
otherBias("biases"),
userFactors("features"))
.as($(newCol)))
Any argument that is passed directly to the UDF has to be a Column
so if you want to pass constant array you'll have to convert it to column literal:
import org.apache.spark.sql.functions.{array, lit}
val myFunc: org.apache.spark.sql.UserDefinedFunction = ???
myFunc(
userBias("bias"),
otherBias("biases"),
userFactors("features"),
// org.apache.spark.sql.Column
array(context.map(xs => array(xs.map(lit _): _*)): _*)
)
Non-Column
objects can be passed only indirectly using closure, for example like this:
def myFunc(context: Array[Seq[String]]) = udf {
(userBias: Float, otherBiases: Map[Long, Float], userFactors: Seq[Float]) =>
???
}
myFunc(context)(userBias("bias"), otherBias("biases"), userFactors("features"))
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