Mex C++ create std::vector<double> from TypedArray<double>

Question

Matt 2019-4-3

1
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/454154-mex-c-create-std-vector-double-from-typedarray-double

编辑： Daniele Nanni 2022-1-26

I'm using mex and C++, and I'm trying to convert a Matlab TypedArray<double> into a c++ std::vector<double>

ObjectArray obj(inputs[0]);
std::shared_ptr<matlab::engine::MATLABEngine> matlabPtr = getEngine();
matlab::data::TypedArray<double> foo = matlabPtr->getProperty(obj, u"foo")

I'm trying to avoid the below, just looping through and adding each value because that seems very inefficient on large vectors.

std::vector<double> bar;
for (auto& elem : inArray) {
    bar.push_back(inArray);
}

I was hoping there was some way of just accessing the underlying vector directly.

std::vector<double> bar = foo.someFunc()

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Answer 1

Amit P 2019-5-9

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/454154-mex-c-create-std-vector-double-from-typedarray-double#answer_374229

在 MATLAB Online 中打开

You can use the iterator available in the TypedAray.

ObjectArray obj(inputs[0]);
std::shared_ptr<matlab::engine::MATLABEngine> matlabPtr = getEngine();
matlab::data::TypedArray<double> foo = matlabPtr->getProperty(obj, u"foo")
//Use the iterator here
std::vector<long double> dest(foo.begin(), foo.end());

Hopefully this helps.

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Chen Dadon 2019-9-18

在 MATLAB Online 中打开

Hi, do you know if i can cast TypedArray to cpp variable?

lets say i create matrix and my function to modify this matrix can get only ptr to float how can i cast the ptr?

TypedArray<float> Mat = factory.createArray<float>({ Height , uiWidth });
float *pWrapedMat = (float*)Mat; //crash
m_mfImage.Init(Height, uiWidth, pWrapedMat);//wraping the matrix
aOutput.m_pmuiImage = &m_mfImage;
//Execute Algorithm
m_Alg.Execute(&aInput, &aOutput);//create frame output
outputs[0] = std::move(aOutput);

Daniele Nanni 2022-1-26

编辑：Daniele Nanni 2022-1-26

Hi,

It work smooth for a single vector, but what if the obj is a matrix?

I have tried your solution and when I apply:

ObjectArray obj(inputs[0]); // Obj_INET_ONET

TypedArray<std::complex<float>> inet_matrix = matlabPtr->getProperty(obj, u"inet_matrix");

matlab::data::ArrayDimensions size_matrix = inet_matrix.getDimensions();

std::vector<std::complex<float>> inet_vec(inet_matrix.begin(), inet_matrix.end());

the inet_vec contains the matrix inet_matrix (40x8) as a long vector (so as 1x40*8). I need to have a matrix in c++ for do some operations in the script and then send back to matlab the result. How can I do that?

Thanks since now for your time to answer me!

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