a Visual C++ library that allows you to plot just as in Matlab.
Click here for the Chinese page of this project. The library can be used in a Console program as well as any other Visual C++ program. To use MatPlot, you just need to include MatPlot.h, set the linker to input MatPlot.lib and copy MatPlot.dll to your project folder. For a detailed tutorial on how to do this in Visual Studio 2017, please read the wiki.
#include <Windows.h>
#include <cmath>
#include "MatPlot.h"
using namespace MatPlot;
int main()
{
double x[5]{ 1,2,3,4,5 };
double y[5]{ 1,3,2,4,3 };
int N{ 5 };
MatPlotInit();
plot(x, y, N);
Sleep(60000);
MatPlotClose();
return 0;
}
Note that every function in MatPlot has namespace MatPlot. Use MatPlotInit() and MatPlotClose() to initialize and close MatPlot. They can be used only once in a program, every MatPlot function must be invoked between MatPlotInit() and MatPlotClose(). Use Sleep() function so that the figure does not close immediately.
plot() function's prototype is
plot(double *px, double *py, int N, char color = 'a');
where px and py could be array names or pointers, N is the number of elements in px and py, color is a single character indicating the color. The default value a means automatic, which means the color will change every time plot() or scatter() is used. Like in Matlab, the possible color values can be 'r'(red), 'g'(green), 'b'(blue), 'y'(yellow), 'm'(magenta), 'c'(cyan), 'k'(black), 'w'(white). plot() always operate on the current figure, if there is none opened yet, figure1 will be created.
scatter() function scatters '+' shaped data points on a figure, its prototype is the same as figure(), you can add the following line under plot(...); in the above example.
scatter(x, y, N);
Note that the color has become orange now.
figure() function creates new figure dialog, the prototype is
figure(int FigNo = -1);
In the default case, figure() will number the dialogs starting from one. If there is a positive FigNo input, figure dialog with number (FigNo + 1) will be generated (since C++ is 0 based). figure() can also be used to specify the current figure for functions such as plot() and scatter() to work on.
close() function closes a figure, the prototype is
close(int FigNo = -1);
In the default case, it will close the current figure. When used with an argument, it will close the (FigNo + 1)th figure. In both cases, if the current figure is closed, the current figure will become the next opened figure with a larger number, if there is none, an opened figure with a smaller number is used. Closing a figure by clicking X button is the same as using a close() function.
close_all() function closes all opened figures.
clf() (clean figure) function cleans the current figure, and set the axis range from 0 to 1.
axis() function changes the axis range, its prototype is
axis(double xmin, double xmax, double ymin, double ymax);
where the arguments are the minimum and maximum values for x and y axis.
axis_auto() function sets the axis to adjust itself automatically (this is the default for new figures). If any data point in plot() or scatter() falls out of range, the axis will expand its range to include these points.
axis_manual() function sets the axis to only be adjusted manually.
xticks() and yticks() function sets the axis ticks, the prototypes are both
xticks(double tickmin, double tickmax, int Nticks = 26, int txtstart = 0, int txtspace = 5, int Ndigits = 2);
where tickmin and tickmax are the coordinates of ticks with minimum and maximum values, Nticks is the number of ticks. The longer ticks and text are displayed every txtspace ticks. The text has Ndigits digits (no scientific notation yet).
The coordinate arrangement is not as smart as that in Matlab yet. To demonstrate, let's plot a sine curve.
#include <Windows.h>
#include <cmath>
#include "MatPlot.h"
using namespace MatPlot;
int main()
{
const int N{ 100 };
const double pi{ 3.1415926 };
double x[N]{};
double y[N]{};
for (int i{}; i < N; i++)
{
x[i] = 2 * pi / (N - 1) * i;
y[i] = sin(x[i]);
}
MatPlotInit();
plot(x, y, N);
//xticks(0, 6.2, 32, 0, 5, 1);
Sleep(60000);
MatPlotClose();
return 0;
}
We can see that the arrangement of ticks in the x axis is not reasonable. We can use xticks() function to rearrange. Uncomment the line
xticks(0, 6.2, 32, 0, 5, 1);
to set the minimum tick to 0, the maximum tick to 6.2, with a total of 32 ticks. From the first tick, print a coordinate every 5 ticks, and round to the first decimal number. The resulting plot is
