格式化输出，可输出的类型（OpenCV案例源码cout_mat.cpp解读）

格式化输出风格： OpenCV, matlab, python, numpy, csv 和 C 风格

可输出的类型：矩阵、点（二维、三维）、图、容器

#include <opencv2/opencv.hpp>
#include <iostream>
using namespace std;
using namespace cv;

int main()
{
    //单位矩阵，主对角线是1
    Mat I = Mat::eye(4, 4, CV_64F);
    I.at<double>(1,1) = CV_PI;//第2行2列的值赋值为PI
    cout << "I = \n" << I << ";" << endl << endl;
    
    //图
    Mat r = Mat(10, 3, CV_8UC3);//10*3的3通道矩阵
    randu(r, Scalar::all(0), Scalar::all(255));//元素被赋值[0,255)随机值
    cout << "默认风格= \n" << r << ";" << endl << endl;
    cout << "matlab风格= \n" << format(r, Formatter::FMT_MATLAB) << ";" << endl << endl;
    cout << "python风格= \n" << format(r, Formatter::FMT_PYTHON) << ";" << endl << endl;
    cout << "numpy风格= \n" << format(r, Formatter::FMT_NUMPY) << ";" << endl << endl;
    cout << "csv风格= \n" << format(r, Formatter::FMT_CSV) << ";" << endl << endl;
    cout << "c风格= \n" << format(r, Formatter::FMT_C) << ";" << endl << endl;

    //二维点
    Point2f p(5, 1);
    cout << "p = " << p << ";" << endl;

    //二维点对象的容器，20个点
    vector<Point2f> points(20);
    for (size_t i = 0; i < points.size(); ++i)
        points[i] = Point2f((float)(i * 5), (float)(i % 7));//横坐标是5的倍数，纵坐标是7的余数
    cout << "points = " << points << ";" << endl;

    //浮点型对象的容器，元素是1，2，3
    vector<float> v;
    v.push_back(1);
    v.push_back(2);
    v.push_back(3);
    cout << "shortvec = " << Mat(v) << endl;

    return 0;
}