如何在C中传递gnuplot矩阵并绘制pm3d映射? [英] How to pass gnuplot a matrix and splot pm3d map in c?

问题描述

因此，这一次，我有一个名为zvalue[10][10]的矩阵，我想绘制一个具有常规x-y网格并且以zvalue[i][j]为点(i,j)的值的pm3d贴图.

So, this time, I have a matrix called zvalue[10][10], and I would like to draw a pm3d map, with normal x-y grids, and with zvalue[i][j] to be the value of point (i,j).

在gnuplot中，我只使用:

In gnuplot, I just use:

set pm3d map
splot zvalue matrix using 1:2:3 with pm3d

在C++ gnuplot管道中，我可以使用函数gp.file1d()来实现这一目标.

And in C++ gnuplot pipes, I can use a function gp.file1d() to achieve this.

gp << "splot" << gp.file1d(matrix) << "matrix using 2:1:3" << "with pm3d\n"

但是现在，我在C gnuplot管道中，当然我可以将矩阵写入名为zvalue.txt的文件中，并使用以下命令:

But now, I am in C gnuplot pipe, of course I can write the matrix into a file called zvalue.txt, and use the following:

fprintf(gp, "splot \"zvalue.txt\" matrix using 1:2:3 with pm3d\n")

但是还有其他方法吗?当我使用矩阵处理普通散点图时，我尝试了@Christ的建议，即执行以下操作:

But is there other way? I tried @Christ's suggestion when I deal with normal splot with matrix, that is do something like:

int main(void)
{
    FILE *gp = popen(GNUPLOT, "w");

    fprintf(gp, "splot '-' matrix using 1:2:3\n");
    int i, j;
    for (i = 0; i < 10; i++) {
        for (j = 0; j < 10; j++)
            fprintf(gp, "%d ", i*j);
        fprintf(gp, "\n");
    }
    pclose(gp);
    return 0;
}

但是当它是pm3d时，它不能很好地工作.我还逐点尝试了splot，这对于带有矩阵的标称散点图非常有效，但是在这里，对于pm3d，则没有任何效果.

But when it's pm3d, it does not work well. I also tried with splot point by point, which works well for nomal splot with matrix, but here with pm3d, nothing works.

推荐答案

以下脚本在pm3d上可以正常使用:

The following script works fine with pm3d:

#include <stdio.h>
#define GNUPLOT "gnuplot -persist"

int main(void)
{
    FILE *gp = popen(GNUPLOT, "w");

    fprintf(gp, "set pm3d map\n");
    fprintf(gp, "splot '-' matrix using 1:2:3 with pm3d\n");
    int i, j;
    for (i = 0; i < 10; i++) {
        for (j = 0; j < 10; j++)
            fprintf(gp, "%d ", i*j);
        fprintf(gp, "\n");
    }
    pclose(gp);
    return 0;
}

因此，如果您有一个使用pm3d且无法正常工作的程序，那么确实可以准确地看到 完整文件(以便您可以将代码复制并粘贴到进行编译和测试).

So if you have a program which makes use of pm3d and doesn't work, it would really help to see exactly that full file (so that one can copy&paste the code to compile and test it).

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