CODEWITHSUNDEEP
c++opencv
Humam Helfawi
Humam Helfawi

Reputation: 20294

Read YML in OpenCV without knowing the matrix name

Is it possible YML file in OpenCV and retrieve the first matrix in the file without knowing its name? I usuaully do it like this:

cv::FileStorage fs("foo.yml", cv::FileStorage::READ);
cv::Mat bar;
fs["A"] >> bar;

How to achieve this without knowing that A is named A?

I am interested in a solution that does not manually parse the file and figuring out the name.

Upvotes: 1

Views: 105

Answers (1)

Miki
Miki

Reputation: 41775

If you know the structure of the YML, you can navigate it using FileNode, and retrieve the elements:

#include <opencv2\opencv.hpp>

int main()
{
    cv::Mat1b src(2, 3);
    cv::randu(src, 0, 256);

    { 
        // Create a simple YML file
        cv::FileStorage fs("test.yml", cv::FileStorage::WRITE);
        fs << "foo" << src;
    }

    // Read the saved data without knowing the name
    cv::FileStorage fs("test.yml", cv::FileStorage::READ);

    // Get first node
    cv::FileNode fn = fs.getFirstTopLevelNode();

    // Get its name
    cv::String name = fn.name();

    // Retrieve data as usual
    cv::Mat res;
    fs[name] >> res;

    // Or directly from the FileNode
    cv::Mat res2;
    fn >> res2;

    return 0;
}

Upvotes: 1

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