CODEWITHSUNDEEP
swiftcoreml
SFlow
SFlow

Reputation: 293

Adding elements to a MLMultiArray

I have a CoreML model (created using TF and converted to CoreML). For it 

input is: MultiArray (Double 1 x 40 x 3)
output is: MultiArray (Double)

I will be getting these [a,b,c] tuples and need to collect 40 of them before sending into to the model for prediction. I am looking through the MLMultiArray documentation and am stuck. May be because of I am new to Swift.

I have a variable called modelInput that I want to initialize and then as the tuples come in, add them to the modelInput variable. 

modelInput = MLMultiArray(shape:[1,40,3], dataType:MLMultiArrayDataType.double))

The modelInput.count is 120 after this call. So I am guessing an empty array is created.

However now I want to add the tuples as they come in. I am not sure how to do this. For this I have a currCount variable which is updated after every call. The following code however gives me an error. 

"Value of type 'UnsafeMutableRawPointer' has no subscripts"

    var currPtr : UnsafeMutableRawPointer = modelInput.dataPointer + currCount
    currPtr[0] = a
    currPtr[1] = b
    currPtr[2] = c
    currCount = currCount + 3

How do I update the multiArray?

Is my approach even correct? Is this the correct way to create a multi array for the prediction input?

I would also like to print the contents of the MLMultiArray. There doesn't appear to be any helper functions to do that though.

Upvotes: 0

Views: 1310

Answers (2)

Matthijs Hollemans
Matthijs Hollemans

Reputation: 7892

You can use pointers, but you have to change the raw pointer into a typed one. For example:

let ptr = UnsafeMutablePointer<Float>(OpaquePointer(multiArray.dataPointer))
ptr[0] = a
ptr[1] = b
ptr[2] = c

Upvotes: 1

SFlow
SFlow

Reputation: 293

I figured it out. I have to this -- 

    modelInput[currCount+0] = NSNumber(floatLiteral: a)
    modelInput[currCount+1] = NSNumber(floatLiteral: b)
    modelInput[currCount+2] = NSNumber(floatLiteral: c)

I cannot use the raw pointer to access elements.

Upvotes: 0

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