C++ 如何使用浮点数组中的数据初始化 cv::Mat
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How can I initialize a cv::Mat with data from a float array
提问by Brett
I need to create a cv::Matvariable that is initialized with my data from a float *array.
This should be basic, but I'm having trouble figuring it out.
我需要创建一个cv::Mat用float *数组中的数据初始化的变量。这应该是基本的，但我无法弄清楚。
I have the code:
我有代码：
float *matrixAB = <120 floating point array created elsewhere>;
cv::Mat cv_matrixAB = cv::Mat(12, 10, CV_32F, &matrixAB);
but cv_matrixABnever contains floatvalues, and more importantly doesn't match the data contained in matrixAB.
但从cv_matrixAB不包含float值，更重要的是不匹配包含在matrixAB.
If I change the line to:
如果我将行更改为：
cv::Mat cv_matrixAB = cv::Mat(12, 10, CV_32F, matrixAB);
then the cv_matrixAB.dataare all 0. I have also tried using CV_64Fas the type, but I see the same behaivor.
那么cv_matrixAB.data都是0。我也尝试使用CV_64Fas 类型，但我看到了相同的行为。
Can anyone help me identify where I am going wrong?According to the cv::Matconstructor documentation, I should be able to provide my data in the form of a float *array.
谁能帮我确定我哪里出错了？根据cv::Mat构造函数文档，我应该能够以float *数组的形式提供我的数据。
Update:a little more info here:
Even the following code does not work. The printfdisplays 63, which of course is not a value in dummy_query_data.
更新：这里有更多信息：即使下面的代码也不起作用。的printf显示器63，这当然不是一个值dummy_query_data。
float dummy_query_data[10] = { 1, 2, 3, 4,
5, 6, 7, 8 };
cv::Mat dummy_query = cv::Mat(2, 4, CV_32F, dummy_query_data);
printf("%f\n", (float)dummy_query.data[3]);
回答by herohuyongtao
You're doing fine. But you should access the mat element by using at<float>()instead of .data(which will give you uchar *). Or simply use cout << mat;to print all its elements. It will give you the expected result.
你做的不错。但是你应该使用at<float>()而不是访问 mat 元素.data（这会给你uchar *）。或者简单地用于cout << mat;打印其所有元素。它会给你预期的结果。
float dummy_query_data[10] = { 1, 2, 3, 4, 5, 6, 7, 8 };
cv::Mat dummy_query = cv::Mat(2, 4, CV_32F, dummy_query_data);
cout << dummy_query.at<float>(0,2) << endl;
cout << dummy_query << endl;
It will output:
它会输出：
3
[1, 2, 3, 4;
5, 6, 7, 8]
