Converting coder::array<unsigned char, 3U> to unsigned char
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I am using Matlab coder to generate c++ codes for a script i have made. The output datatype of MATLAB coder is coder::array<unsigned char, 3U>. Would you please help me figure out how to convert this into unsigned char so that i can use it in opencv.
Thank you
1 commentaire
Alexander Bottema
le 24 Août 2022
To directly access the underying data of a coder::array you can use the ".data()" method. The total number of elements can be computed via the ".numel()" method. Size of each dimension is available via the ".size(dimension)" method.
I attached a full example (see example.zip).
example.m:
function y = example(n)
y = zeros(n,n,n,'uint8');
for i = 1:numel(y)
y(i) = 64 + i;
end
main.cpp:
#include <iostream>
#include "example.h"
#include "coder_array.h"
int main(int argc, char **argv[])
{
(void)argc;
(void)argv;
coder::array<unsigned char, 3U> out;
example(2, out);
int n = out.numel();
unsigned char *data = out.data();
for (int i = 0; i < n; i++) {
std::cout << data[i];
}
std::cout << std::endl;
return 0;
}
doit.m:
cfg = coder.config('exe');
cfg.TargetLang = 'C++';
codegen -args 0 -config cfg example main.cpp
And running the executable gives:
>> !example (!./example on Linux)
ABCDEFGH
Réponses (1)
Anirban Ghosh
le 24 Août 2022
Hi Abhijith,
Please refer to this documentation page for information on using the coder:array template: Use Dynamically Allocated C++ Arrays in Generated Function Interfaces. In particular, note the "Using the coder::array Class Template" section and the two examples that follow.
If your output (say myArray) is of type coder::array<unsigned char, 3U>, it contains elements of type unsigned char and has 3 dimensions.
- To access the sizes of the three dimensions, call the size method: myArray.size(0), myArray.size(1), and myArray.size(2).
- To access the (i,j,k)-th element of myArray, call the at method: myArray.at(i,j,k). This call will return the unsigned char value stored at that location.
- In your code, you can pre-allocate an unsigned char array and populate it with these values.
1 commentaire
cui,xingxing
le 23 Fév 2023
Modifié(e) : cui,xingxing
le 23 Fév 2023
How should I set the data elements of coder::array if the other way around?(Instead of copying element by element, the in-place method), I'm following the linked documentation and trying myself, but unfortunately I couldn't make it work!
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