(Extra) C++ Image Export & Matplot++

Slides version: lecture16_slides.html
Website version: lecture16.html

• Tutorial: Matplot++
  • Installation
  • Hello world
  • Plot Functions
  • Annotations
  • Appearance
  • Export to image
• Example: Plot a Geometry on Complex Plane
• Pratices

Installation

Windows + MinGW: Update gcc

Note: 須先完成 設定 VSCode 環境 (Windows + MinGW) 再進行下一步

Terminal:

# remove old gcc 8.1.0
scoop uninstall mingw
# install new gcc 12.1.0
scoop install mingw-winlibs

Linux/macOS: Install CMake

Terminal:

Linux

sudo apt install cmake

macOS

brew install cmake

Install gnuplot

Terminal:

Windows

scoop install gnuplot

Linux

sudo apt install gnuplot

macOS

brew install gnuplot

Note: 安裝完成後須重新啟動 VSCode 及重新打開 Terminal 才能生效

Update VSCode C/C++ Extension

Install C/C++ Extension Pack

Correct:

Install Matplot++

Download project file & open in VSCode:

1. github link stevenokm/matplotplusplus-master.zip
2. 解壓縮全部，解壓縮後會有一個 matplotplusplus-master 目錄
3. 使用 VSCode 打開 matplotplusplus-master 目錄

Build Matplot++ & Test Matplot++

1. configure project "matplotplusplus-master" (Yes)

2. select right active kit
   1. Windows: GCC 12.1.0 x86_64-w64-mingw32
   2. Linux: GCC 9.4.0 x86_64-linux-gnu (Ubuntu 20.04)
   3. macOS: Clang 13.0.0 arm64-apple-darwin20.6.0 (macOS Big Sur, Apple Silicon)

3. Press "Build" button on the bottom of the VSCode window

4. Press "Run" button on the bottom of the VSCode window

5. Press "Debug" button on the bottom of the VSCode window to debug

Note 要注意 CMake 的設定是在 Debug CMake: [Debug] 下執行的

Hello world

Ref: Bar Plot - Matplot++

#include <cmath>
#include <matplot/matplot.h>

int main()
{
    using namespace matplot;

    std::vector<double> y = {75, 91, 105, 123.5, 131, 150,
                             179, 203, 226, 249, 281.5};
    bar(y);

    show();
    return 0;
}

Result:

Plot Functions

• Line Plot
• Histogram
• Scatter Plot
• Bar Plot
• Pareto Chat
• Polar Line Plot

Line Plot

Ref: Line Plot - Matplot++

#include <cmath>
#include <matplot/matplot.h>

int main()
{
    using namespace matplot;

    std::vector<int> y = {2, 4, 7, 7, 6, 3, 9, 7, 3, 5};
    plot(y);

    show();
    return 0;
}

Result:

Histogram

Ref: Histogram - Matplot++

#include <cmath>
#include <matplot/matplot.h>
#include <random>

int main()
{
    using namespace matplot;

    std::vector<double> x = randn(10000, 0, 1);

    auto h = hist(x);
    std::cout << "Histogram with " << h->num_bins() << " bins" << std::endl;

    show();
    return 0;
}

Result:

Scatter Plot

Ref: Scatter Plot - Matplot++

#include <matplot/matplot.h>
#include <random>

int main()
{
    using namespace matplot;

    auto x = linspace(0, 3 * pi, 200);
    auto y = transform(x, [&](double x)
                       { return cos(x) + rand(0, 1); });

    scatter(x, y);

    show();
    return 0;
}

Result:

Bar Plot

Ref: Bar Plot - Matplot++

#include <cmath>
#include <matplot/matplot.h>
#include <random>

int main()
{
    using namespace matplot;

    std::vector<std::vector<double>> Y = {
        {2, 2, 2, 2}, {2, 5, 8, 11}, {3, 6, 9, 12}};
    bar(Y);

    show();
    return 0;
}

Result:

Pareto Chat

Ref: Pareto Chat - Matplot++

#include <cmath>
#include <matplot/matplot.h>
#include <random>

int main()
{
    using namespace matplot;

    std::vector<double> codelines = {200, 120, 555, 608, 1024, 101, 57, 687};
    std::vector<std::string> coders = {"Fred", "Ginger", "Norman", "Max",
                                       "Julia", "Wally", "Heidi", "Pat"};

    pareto(codelines, coders);
    title("Lines of Code by Programmer");

    show();
    return 0;
}

Result:

Polar Line Plot

Ref: Polar Line Plot - Matplot++

#include <cmath>
#include <matplot/matplot.h>

int main()
{
    using namespace matplot;

    std::vector<double> theta_degrees = linspace(0, 360, 50);
    std::vector<double> rho =
        transform(theta_degrees, [](auto t)
                  { return 0.005 * t / 10.; });
    std::vector<double> theta_radians = deg2rad(theta_degrees);
    polarplot(theta_radians, rho);

    show();
    return 0;
}

Result:

Annotations

• Text
• Text with Arrow
• Rectangle
• Textbox

Text

Ref: Text - Matplot++

#include <cmath>
#include <matplot/matplot.h>

int main()
{
    using namespace matplot;

    std::vector<double> x = linspace(-5, +5);
    std::vector<double> y =
        transform(x, [](auto x)
                  { return pow(x, 3) - 12 * x; });
    plot(x, y);

    std::vector<double> xt = {-2, +2};
    std::vector<double> yt = {16, -16};
    std::string str = "dy/dx = 0";
    text(xt, yt, str);

    show();
    return 0;
}

Result:

Text with Arrow

Ref: Text with Arrow - Matplot++

#include <cmath>
#include <matplot/matplot.h>

int main()
{
    using namespace matplot;

    plot(iota(1, 10));
    auto [t, a] = textarrow(2.5, 6.5, 5, 5, "y=x");
    t->color("red").font_size(14);
    a->color("blue");

    show();
    return 0;
}

Result:

Rectangle

Ref: Rectangle - Matplot++

#include <cmath>
#include <matplot/matplot.h>

int main()
{
    using namespace matplot;

    rectangle(2, 4, 2, 2, 1.);
    auto r2 = rectangle(2, 4, 2, 2, 0.);
    r2->color("red");
    axis(equal);

    show();
    return 0;
}

Result:

Textbox

Ref: Textbox - Matplot++

#include <cmath>
#include <matplot/matplot.h>

int main()
{
    using namespace matplot;

    plot(iota(1, 10));
    textbox(2, 8, 4, 0.5, "String line from 1 to 10");

    show();
    return 0;
}

Result:

Export to image

• Manually
• Programmatically

Manually

1. Click on the Export to image button

2. Type filename

ProgProgrammatically

Export files with save()

#include <cmath>
#include <matplot/matplot.h>

int main()
{
    using namespace matplot;

    plot(iota(1, 10));
    textbox(2, 8, 4, 0.5, "String line from 1 to 10");

    // show();

    // windows gnuplot bug workaround
    save("../textbox_export.png");

    // export to file with fileextension .png
    save("../textbox_export.png");
    // or with filename and filetype
    save("../textbox_export", "svg");

    return 0;
}

Result: textbox_export.png

Result: textbox_export.svg

Example: Plot a Geometry on Complex Plane [Source]

Pratices

• Draw & Save Triangle_2D in 2D plane by matplot++
• Draw & Save Triangle_Comp in Polar Complex plane by matplot++