Gnuplot极坐标图直方图 [英] Gnuplot Polar Coodinates Histogram

问题描述

我有一个数据文件 file.dat ，其中包含平面中各点的三列(半径，角度，温度)，我想使用极性坐标和色图将数据绘制为直方图，如下图所示，但使用gnuplot.我可以使用所需的垃圾箱值创建一个 histogram.dat 文件，但我不知道如何在gnuplot中绘制该文件

解决方案

据我所知，gnuplot中没有立即使用的极性热图"绘图样式(但我可能是错的，至少，我没有看到演示页上的示例).因此，您必须自己实施.

基本上，必须为每个数据点绘制一个填充的线段.因此，对于每个数据点，您都必须在该单个线段的圆周上创建点.然后，您可以使用填充曲线和特定颜色来绘制此段.

假设:

• 数据位于规则的网格/角度( astep )和半径( rstep )的阶梯中.
• 数据位于数据块中(如何将其从文件获取到数据块中，请参见

  I have a data file file.dat with three columns (radio, angle, Temperature) for points in the plane, and I want to plot this data as a histogram using polar coordenates and color maps, like in the figure below but using gnuplot. I can create a histogram.dat file with the values of the bins that I want but I don't know how to plot it in gnuplot

  解决方案

  To my knowledge there is no right-away "polar heatmap" plotting style in gnuplot (but I could be wrong, at least, I haven't seen an example on the demo page). Hence, you have to implement it yourself.

  Basically, for each datapoint you have to plot a filled segment. Therefore, for each datapoint you have to create points on the circumference of this single segment. Then you can plot this segment with filledcurves and a specific color.

  Assumptions:

  • data is in a regular grid/steps in angle (astep) and radius (rstep).
  • data is in a datablock (how to get it from a file into a datablock, see gnuplot: load datafile 1:1 into datablock)
  • separators are whitespaces
  • no header lines

  Further optimization potential:

  • automatic extraction of astep and rstep.

  I hope you can adapt the code to your needs.

  Code:

  ### workaround for polar heatmap
  reset session
  
  set size square
  set angle degrees
  unset border
  unset tics
  set cbtics
  set polar
  set border polar
  unset raxis
  
  # create some test data
  f(a,r) = r*cos(a) * r*sin(a) + rand(0)*100
  set print $Data
      do for [a=0:350:10] {
          do for [r=1:20] {
              print sprintf("%g %g %g",a,r,f(a,r))
          }
      }
  set print
  
  astep = 10
  rstep = 1
  
  # create the segments for each datapoint
  set print $PolarHeatmap
      do for [i=1:|$Data|] {
          a = real(word($Data[i],1))
          r = real(word($Data[i],2))
          c = real(word($Data[i],3))
          do for [j=-5:5] {
              print sprintf("%g %g %g",a+j*astep/10., r-0.5*rstep, c)
          }
          do for [j=5:-5:-1] {
              print sprintf("%g %g %g",a+j*astep/10., r+0.5*rstep, c)
          }
          print ""
          print ""
      }
  set print
  
  set style fill noborder
  set palette defined (0 "blue", 1 "grey", 2 "green")
  
  plot $PolarHeatmap u 1:2:3 w filledcurves palette notitle
  ### end of code
  

  Result:

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