How to pass two-dimensional array to User defined functions?

Question

Using UDF implies that each factor c1, c2, c3 must be passed by parameter independently. Is there any flexible solution, e.g. how to pass a sequence of these factors to UDF?

val myFunction = udf {
      (userBias: Float, productBias: Float, productBiases: Map[Long, Float],
        userFactors: Seq[Float], productFactors: Seq[Float], c1: String, c2: String, c3: String) =>

        var result = Float.NaN

        // result calculation

        result
    }

And then I call this function the following way (dataset is a DataFrame):

myFunction(userBias("bias"), 
           productBias("bias"),
           productBias("biases"),
           userFactors("features"), 
           productFactors("features"),
           dataset(factors(0)), dataset(factors(1)), dataset(factors(2))

If I do something like this, then the compiler says "Not applicable":

val myFactors = dataset.select(factors.head, factors.tail: _*)

myFunction(userBias("bias"), 
           productBias("bias"),
           productBias("biases"),
           userFactors("features"), 
           productFactors("features"),
           myFactors)

Answer 1

If you have a 2d array like this:

val xy = Array.ofDim[Int](numrows, numcolumns);
isFunction(xy);

Your function definition for isFunction would look like this:

def isFunction(arg: Array[Array[Int]]){
    println(arg(i)(0)); // how to access array element