How to initialize a MLMultiArray in CoreML

Question

I\'ve got an array of 40 arrays with 12 double features, so the type is [[double]]. Currently I\'m sending this data to Google Cloud ML API to get a related prediction.

Answer 1

I achieved it by reading this blog :)

let data = _currentScaledMotionArrays.reduce([], +) //result is of type [Double] with 480 elements
guard let mlMultiArray = try? MLMultiArray(shape:[40,12], dataType:MLMultiArrayDataType.double) else {
    fatalError("Unexpected runtime error. MLMultiArray")
}
for (index, element) in data.enumerated() {
    mlMultiArray[index] = NSNumber(floatLiteral: element)
}
let input = PredictionModelInput(accelerations: mlMultiArray)
guard let predictionOutput = try? _predictionModel.prediction(input: input) else {
        fatalError("Unexpected runtime error. model.prediction")
}

Answer 2

This is how I did it. Probably not the best way to handle optionals but gets the job done for testing

Create an instance of the MLMultiArray object with shape and data type

let mlArray = try? MLMultiArray(shape: [3], dataType: MLMultiArrayDataType.float32)

mlArray does not have an append function so you literally have to iterate through it and add values

for i in 0..<array.count {
     mlArray?[i] = NSNumber(value: input[i])
}

Full function

    func convertToMLArray(_ input: [Int]) -> MLMultiArray {

        let mlArray = try? MLMultiArray(shape: [3], dataType: MLMultiArrayDataType.float32)


        for i in 0..<array.count {
            mlArray?[i] = NSNumber(value: input[i])
        }


        return arr!
    }