如何在gnuplot中制作蜘蛛图？

Question

假设我的数据采用以下形式：

#atom a b c
43 1.2 1.3 1.4
44 1.2 1.4 1.8
45 1.3 1.8 1.9
46 2.0 2.3 2.4
47 1.5 1.6 1.8

我想要这样的情节http://www.r-graph-gallery.com/143-spider-chart-with-saveral-individuals/（中间那个）。

我该怎么做？

ps。这里的标题 (How to Create a Spider Plot in Gnuplot?) 具有误导性...

Answer 1

据我所知，没有内置功能可以直接为您提供链接输出。不过，人们可以使用 Gnuplot 提供的工具即兴发挥。策略是：

1. 分析文件并确定顶点数
2. 在参数模式下生成“多边形”网格
3. 使用filledcurves 绘图样式（具有透明度）绘制数据

例如（数据表示为数据块，而不是直接传递文件）：

reset session
set terminal pngcairo enhanced font "Times,16"
set output 'plot.png'

$DATA << EOD
#atom a b c
43 1.2 1.3 1.4
44 1.2 1.4 1.8
45 1.3 1.8 1.9
46 2.0 2.3 2.4
47 1.5 1.6 1.8
EOD

stats $DATA nooutput

N = STATS_columns
M = STATS_records

set angles degrees
set size ratio -1
set style fill transparent solid 0.25

unset key
unset border
unset xtics
unset ytics

colors = "dark-red royalblue forest-green"

set style line 42 lt 1 lc rgb '#333333' dt 3 lw 0.8

deltaR = 0.5
maxR = 3 + deltaR/4
numOfStepsInR = floor((1.*maxR) / deltaR)

#helper functions
alpha(i) = 90. - i*360./M
posX(i, r) = cos(alpha(i))*r
posY(i, r) = sin(alpha(i))*r
lcolor(i) = word(colors, i%words(colors) + 1)

do for [i=0:M-1] {
  stats $DATA every ::i::i using (labelValue=$1) nooutput
  set label sprintf("%d", labelValue) at posX(i,maxR),posY(i,maxR) center offset char posX(i,1),char posY(i,1)
}

do for [j=1:numOfStepsInR] {
  set label sprintf("%.1f", j*deltaR) at 0,j*deltaR left offset char 0.5,0 tc rgb '#333333'
}

set parametric
set tr [0:1]

set xr [-1.1*maxR:1.1*maxR]
set yr [-1.1*maxR:1.1*maxR]

plot \
  for [i=0:M-1] \
    (cos(alpha(i))*(deltaR*(1-t)+t*maxR)),(sin(alpha(i))*(deltaR*(1-t)+t*maxR)) w l ls 42, \
  for [i=0:M-1] for [j=1:numOfStepsInR] \
    (j*deltaR*cos(alpha(i))*t + (1-t)*j*deltaR*cos(alpha(i+1))),(j*deltaR*sin(alpha(i))*t + (1-t)*j*deltaR*sin(alpha(i+1))) w l ls 42, \
  for [i=2:N] $DATA u (posX($0, column(i))):(posY($0, column(i))) w filledcurves closed fc rgb lcolor(i-2) fs border lc rgb lcolor(i-2) lw 2, \
  for [i=2:N] $DATA u (posX($0, column(i))):(posY($0, column(i))) w p ps 1.2 pt 7 lc rgb lcolor(i-2)

这会产生：