从 C++ 调用 GNU 绘图，无需用户输入

call gnu plot from c++ without user input

本文关键字：用户 输入 绘图 C++ 调用 GNU      更新时间：2023-10-16

我在网上找到了这段代码。它使用 gnuplot从 c++ 中生成的数据制作一个绘图。但是，它需要用户输入，没有这些行就无法工作

printf("press enter to continue...");        
getchar();

错误消息显示

line 0: warning: Skipping unreadable file "tempData"
line 0: No data in plot

有人知道解决这个问题的方法吗？我想在循环中使用此代码，而不是每次都调用输入......

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
void plotResults(double* xData, double* yData, int dataSize);
int main() {
int i = 0;
int nIntervals = 100;
double intervalSize = 1.0;
double stepSize = intervalSize/nIntervals;
double* xData = (double*) malloc((nIntervals+1)*sizeof(double));
double* yData = (double*) malloc((nIntervals+1)*sizeof(double));
xData[0] = 0.0;
double x0 = 0.0;
for (i = 0; i < nIntervals; i++) {
x0 = xData[i];
xData[i+1] = x0 + stepSize;
}
for (i = 0; i <= nIntervals; i++) {
x0 = xData[i];
yData[i] = sin(x0)*cos(10*x0);
}
plotResults(xData,yData,nIntervals);
return 0;
}
void plotResults(double* xData, double* yData, int dataSize) {
FILE *gnuplotPipe,*tempDataFile;
char *tempDataFileName;
double x,y;
int i;
tempDataFileName = "tempData";
gnuplotPipe = popen("gnuplot","w");
if (gnuplotPipe) {
fprintf(gnuplotPipe,"plot "%s" with linesn",tempDataFileName);
fflush(gnuplotPipe);
tempDataFile = fopen(tempDataFileName,"w");
for (i=0; i <= dataSize; i++) {
x = xData[i];
y = yData[i];            
fprintf(tempDataFile,"%lf %lfn",x,y);        
}        
fclose(tempDataFile);        
printf("press enter to continue...");        
getchar();        
remove(tempDataFileName);        
fprintf(gnuplotPipe,"exit n"); 
pclose(gnuplotPipe);   
} else {        
printf("gnuplot not found...");    
}
}

我认为实际问题是您将临时文件删除到早期。我会重组代码以：

if (gnuplotPipe) 
{
// Create the temp file
tempDataFile = fopen(tempDataFileName,"w");
for (i=0; i <= dataSize; i++) 
{
x = xData[i];
y = yData[i];            
fprintf(tempDataFile,"%lf %lfn",x,y);        
}        
fclose(tempDataFile);  
// Send it to gnuplot
fprintf(gnuplotPipe,"plot "%s" with linesn",tempDataFileName);
fflush(gnuplotPipe);
fprintf(gnuplotPipe,"exit n"); 
pclose(gnuplotPipe); 
// Clean up the temp file  
remove(tempDataFileName);        
}

这样，您最终不会在系统上获得很多临时文件。

另一个好办法是使 gnuplot 持久化，这样你就能够在管道关闭后看到绘图，只需在打开管道时添加一个-p标志即可

gnuplotPipe = popen("gnuplot -p","w");

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