gnuplot：如何根据网格设置点的大小

Question

我有以下 'data.dat' 文件：

#      x                 y                   z                  radius
  -1.64905083         -1.14142799         -2657.88232          177.358566    
  -449.735321          416.586914         -2865.25366          10.0000000    
   178.955292         -256.291138         -2856.96069          89.9588394
  -336.942322          184.932343         -2839.22876          90.6131058    
  -443.635315         -80.0183029         -2863.29077          70.7404404    
   236.385406          349.893188         -2901.33984          10.0000000    
   485.313416         -366.513947         -2868.35083          10.0000000

球体的位置及其半径。

我的 file.p 读取：

set terminal png size 500,500
set output 'file.png'
set multiplot
set xrange [-1000:1000]
set yrange [-1000:1000]
set zrange [-3000:-2500]
splot "data.dat" using 1:2:3:4 ps variable pt 7
splot -(3000**2-x**2-y**2)**(0.5)

但是 gnuplot 提供给我的点要大得多。我知道这是因为 ps 产生的点比正常大小大 radius 倍。这意味着 ps 不允许设置点的半径，而是设置它比正常点大多少倍。请问如何设置点的半径？

Answer 1

使用“带圆圈”而不是“带第 7 点的点”。

来自手册：

gnuplot> help with circles

 The `circles` style plots a circle with an explicit radius at each data point.
 The radius is always interpreted in the units of the plot's horizontal axis
 (x or x2).  The scale on y and the aspect ratio of the plot are both ignored.
 If the radius is not given in a separate column for each point it is taken from
 `set style circle`.  In this case the radius may use graph or screen coordinates.

 Many combinations of per-point and previously set properties are possible.
 For 2D plots these include

     using x:y
     using x:y:radius
     using x:y:color
     using x:y:radius:color
     using x:y:radius:arc_begin:arc_end
     using x:y:radius:arc_begin:arc_end:color

 By default a full circle will be drawn.  It is possible to instead plot arc
 segments by specifying a start and end angle (in degrees) in columns 4 and 5.

 A per-circle color may be provided in the last column of the using specifier.
 In this case the plot command must include a corresponding variable color
 term such as `lc variable` or `fillcolor rgb variable`.

gnuplot：如何根据网格设置点的大小

gnuplot: how to set the size of the points according to the grid

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