Ubuntu中利用GNUPLOT画NS3产生的数据

（一）直接使用Gnuplot工具

以NS3自带的例子程为例来说明。

进行NS安装目录，下面有/examples/tutorial目录下，有一个拥塞窗口的例子 fifth.cc
把它复制到scratch目录下。

则在后台完成对fifth.cc的运行并把结果存在ns-3.25目录下的fifth.dat中
解释:
“>” 表示输出重定向。
“>”fifth.dat 把执行的结果存入到文件。一般情况下，输出重定向到当前屏幕，>fifth.dat表示输出重定向到该文件。
2>&1 在shell中,文件描述符通常是:STDIN,STDOUT,STDERR,即:0,1,2,
&表示在后台执行， 2>&1 表示，把错误信息stderr也放到stdout中输出.
在dat所在目录下进入GNUPLOT

在gunplot环境下，输入以上命令，会发现在ns-3.25目录下产生fifth.png图

解释：

set termianl png //设置输出图片格式，如png,gif,jpg等

set size width,height //设备图片宽度，高度

set output “图片名称” //设置保存图片名称。

plot title “标题名” //设置图片标题名称，一般用英文，有时不支持中文字符

plot “数据.dat” using 1:2 with linespoints //把数据文件”数据.dat”输出图像， using 1:2,使用第1,2列数据输出.

with linespoints //点用符号，点与点之间用线连接

a plot “数据.dat” //只输出数据点

b plot “数据.dat” with lines //把点连起来，成线。

c plot “数据.dat” with linespoints //点用符号，点与点之间用线连接

d plot ‘file.dat’ using 1:3 with linespoints //使用1,3列绘图

e plot ‘file.dat’ using 1:($3/2) with linespoints //使用第一列与第三列的二分之一绘图

（二）用Gnuplot类

其实就是间接使用Gnuplot工具。

在程序里边加入Gnuplot类，我们可看一个例子：
目录/ns3/ns-allinone-3.25/ns-3.25/src/stats/examples下的gnuplot-example.cc。

把程序复制到scratch目录下边。编译程序：

在ns-3.25目录下边将会产生三个文件：

plot-2d.plt
plot-2d-with-error-bars.plt
plot-3d.plt

在目录ns-3.25执行以下命令:

查看得到的三个文件：

plot-2d.png
plot-2d-with-error-bars.png
plot-3d.png

源代码：

#include <fstream>

#include "ns3/gnuplot.h"

using namespace ns3;

namespace {

//===========================================================================
// Function: Create2DPlotFile
//
//
// This function creates a 2-D plot file.
//===========================================================================

void Create2DPlotFile ()
{
  std::string fileNameWithNoExtension = "plot-2d";
  std::string graphicsFileName        = fileNameWithNoExtension + ".png";
  std::string plotFileName            = fileNameWithNoExtension + ".plt";
  std::string plotTitle               = "2-D Plot";
  std::string dataTitle               = "2-D Data";

  // Instantiate the plot and set its title.
  Gnuplot plot (graphicsFileName);
  plot.SetTitle (plotTitle);

  // Make the graphics file, which the plot file will create when it
  // is used with Gnuplot, be a PNG file.
  plot.SetTerminal ("png");

  // Set the labels for each axis.
  plot.SetLegend ("X Values", "Y Values");

  // Set the range for the x axis.
  plot.AppendExtra ("set xrange [-6:+6]");

  // Instantiate the dataset, set its title, and make the points be
  // plotted along with connecting lines.
  Gnuplot2dDataset dataset;
  dataset.SetTitle (dataTitle);
  dataset.SetStyle (Gnuplot2dDataset::LINES_POINTS);

  double x;
  double y;

  // Create the 2-D dataset.
  for (x = -5.0; x <= +5.0; x += 1.0)
    {
      // Calculate the 2-D curve
      // 
      //            2
      //     y  =  x   .
      //  
      y = x * x;

      // Add this point.
      dataset.Add (x, y);
    }

  // Add the dataset to the plot.
  plot.AddDataset (dataset);

  // Open the plot file.
  std::ofstream plotFile (plotFileName.c_str());

  // Write the plot file.
  plot.GenerateOutput (plotFile);

  // Close the plot file.
  plotFile.close ();
}


//===========================================================================
// Function: Create2DPlotWithErrorBarsFile
//
//
// This function creates a 2-D plot with error bars file.
//===========================================================================

void Create2DPlotWithErrorBarsFile ()
{
  std::string fileNameWithNoExtension = "plot-2d-with-error-bars";
  std::string graphicsFileName        = fileNameWithNoExtension + ".png";
  std::string plotFileName            = fileNameWithNoExtension + ".plt";
  std::string plotTitle               = "2-D Plot With Error Bars";
  std::string dataTitle               = "2-D Data With Error Bars";

  // Instantiate the plot and set its title.
  Gnuplot plot (graphicsFileName);
  plot.SetTitle (plotTitle);

  // Make the graphics file, which the plot file will create when it
  // is used with Gnuplot, be a PNG file.
  plot.SetTerminal ("png");

  // Set the labels for each axis.
  plot.SetLegend ("X Values", "Y Values");

  // Set the range for the x axis.
  plot.AppendExtra ("set xrange [-6:+6]");

  // Instantiate the dataset, set its title, and make the points be
  // plotted with no connecting lines.
  Gnuplot2dDataset dataset;
  dataset.SetTitle (dataTitle);
  dataset.SetStyle (Gnuplot2dDataset::POINTS);

  // Make the dataset have error bars in both the x and y directions.
  dataset.SetErrorBars (Gnuplot2dDataset::XY);

  double x;
  double xErrorDelta;
  double y;
  double yErrorDelta;

  // Create the 2-D dataset.
  for (x = -5.0; x <= +5.0; x += 1.0)
    {
      // Calculate the 2-D curve
      // 
      //            2
      //     y  =  x   .
      //  
      y = x * x;

      // Make the uncertainty in the x direction be constant and make
      // the uncertainty in the y direction be a constant fraction of
      // y's value.
      xErrorDelta = 0.25;
      yErrorDelta = 0.1 * y;

      // Add this point with uncertainties in both the x and y
      // direction.
      dataset.Add (x, y, xErrorDelta, yErrorDelta);
    }

  // Add the dataset to the plot.
  plot.AddDataset (dataset);

  // Open the plot file.
  std::ofstream plotFile (plotFileName.c_str());

  // Write the plot file.
  plot.GenerateOutput (plotFile);

  // Close the plot file.
  plotFile.close ();
}


//===========================================================================
// Function: Create3DPlotFile
//
//
// This function creates a 3-D plot file.
//===========================================================================

void Create3DPlotFile ()
{
  std::string fileNameWithNoExtension = "plot-3d";
  std::string graphicsFileName        = fileNameWithNoExtension + ".png";
  std::string plotFileName            = fileNameWithNoExtension + ".plt";
  std::string plotTitle               = "3-D Plot";
  std::string dataTitle               = "3-D Data";

  // Instantiate the plot and set its title.
  Gnuplot plot (graphicsFileName);
  plot.SetTitle (plotTitle);

  // Make the graphics file, which the plot file will create when it
  // is used with Gnuplot, be a PNG file.
  plot.SetTerminal ("png");

  // Rotate the plot 30 degrees around the x axis and then rotate the
  // plot 120 degrees around the new z axis.
  plot.AppendExtra ("set view 30, 120, 1.0, 1.0");

  // Make the zero for the z-axis be in the x-axis and y-axis plane.
  plot.AppendExtra ("set ticslevel 0");

  // Set the labels for each axis.
  plot.AppendExtra ("set xlabel \"X Values\"");
  plot.AppendExtra ("set ylabel \"Y Values\"");
  plot.AppendExtra ("set zlabel \"Z Values\"");

  // Set the ranges for the x and y axis.
  plot.AppendExtra ("set xrange [-5:+5]");
  plot.AppendExtra ("set yrange [-5:+5]");

  // Instantiate the dataset, set its title, and make the points be
  // connected by lines.
  Gnuplot3dDataset dataset;
  dataset.SetTitle (dataTitle);
  dataset.SetStyle ("with lines");

  double x;
  double y;
  double z;

  // Create the 3-D dataset.
  for (x = -5.0; x <= +5.0; x += 1.0)
    {
    for (y = -5.0; y <= +5.0; y += 1.0)
    {
      // Calculate the 3-D surface
      // 
      //            2      2
      //     z  =  x   *  y   .
      //  
      z = x * x * y * y;

      // Add this point.
      dataset.Add (x, y, z);
    }

    // The blank line is necessary at the end of each x value's data
    // points for the 3-D surface grid to work.
   dataset.AddEmptyLine ();
    }

  // Add the dataset to the plot.
  plot.AddDataset (dataset);

  // Open the plot file.
  std::ofstream plotFile (plotFileName.c_str());

  // Write the plot file.
  plot.GenerateOutput (plotFile);

  // Close the plot file.
  plotFile.close ();
}

} // anonymous namespace


int main (int argc, char *argv[])
{
  // Create a 2-D plot file.
  Create2DPlotFile();

  // Create a 2-D plot with error bars file.
  Create2DPlotWithErrorBarsFile();

  // Create a 3-D plot file.
  Create3DPlotFile();

  return 0;
}