gnuplot绘图异常：数据定义半径与实际绘图半径不符

原本可正常生成饼图切片的gnuplot脚本出现异常，执行脚本如下：

$DATA<<EOD
0.00,0.00,0.7000,90.0000,114.0000
0.00,0.00,1.0000,114.0000,162.0000
0.00,0.00,1.0000,162.0000,234.0000
0.00,0.00,1.0000,234.0000,330.0000
0.00,0.00,1.0000,330.0000,450.0000
EOD
set datafile separator comma
set style data circles
set term windows
unset xtics; unset ytics; unset x2tics; unset y2tics
set grid noxtics
set grid noytics
set xrange [-1.5:1.5]
set yrange [-1.5:1.5]
set border 0
set colorsequence classic
set title "{/Tahoma=22 Plotting with Pies}" textcolor rgb "0xE25822" rotate by 0
set key inside top right opaque fc rgb "0xFFFFFF"
set label 1 "Alpha\n1" at -0.27,1.27 center font "Tahoma:Bold,12" front
set label 2 "Bravo\n2" at -0.97,0.87 center font "Tahoma:Bold,12" front
set label 3 "Charlie\n3" at -1.24,-0.40 center font "Tahoma:Bold,12" front
set label 4 "Delta\n4" at 0.27,-1.27 center font "Tahoma:Bold,12" front
set label 5 "Echo\n5" at 1.13,0.65 center font "Tahoma:Bold,12" front
plot $DATA every ::0::0 using 1:2:3:4:5 with circles fillstyle solid fc rgb "0x007FFF" title "Alpha (6.67%)",\
$DATA every ::1::1 using 1:2:3:4:5 with circles fillstyle solid fc rgb "0x3CD070" title "Bravo (13.33%)",\
$DATA every ::2::2 using 1:2:3:4:5 with circles fillstyle solid fc rgb "0x738678" title "Charlie (20.00%)",\
$DATA every ::3::3 using 1:2:3:4:5 with circles fillstyle solid fc rgb "0xE25822" title "Delta (26.67%)",\
$DATA every ::4::4 using 1:2:3:4:5 with circles fillstyle pattern 4 title "Echo (33.33%)"

异常表现：

• 数据中Alpha切片的半径定义为0.7，其余切片为1.0
• 但生成的图表里，Alpha实际显示半径为1，其余切片为1.4，与设定值完全不符

核心问题是误用了with circles样式绘制扇形切片：

• with circles的设计初衷是绘制完整圆形，不支持通过起始角度:结束角度参数生成扇形
• 当传入5列数据给with circles时，gnuplot不会将第3列识别为绝对半径，而是把它当作散点的大小缩放因子，这个值会结合当前坐标轴范围自动调整，导致实际显示的半径和设定值偏差
• 之前脚本可能因旧版gnuplot的兼容逻辑偶然正常工作，版本更新后参数解读严格化，导致异常显现

把所有with circles替换为with ellipses arc，同时调整using列的对应关系（椭圆需要x/y两个半轴，这里是圆形，所以重复半径列即可）：
修改后的plot命令如下：

plot $DATA every ::0::0 using 1:2:3:3:4:5 with ellipses arc fillstyle solid fc rgb "0x007FFF" title "Alpha (6.67%)",\
$DATA every ::1::1 using 1:2:3:3:4:5 with ellipses arc fillstyle solid fc rgb "0x3CD070" title "Bravo (13.33%)",\
$DATA every ::2::2 using 1:2:3:3:4:5 with ellipses arc fillstyle solid fc rgb "0x738678" title "Charlie (20.00%)",\
$DATA every ::3::3 using 1:2:3:3:4:5 with ellipses arc fillstyle solid fc rgb "0xE25822" title "Delta (26.67%)",\
$DATA every ::4::4 using 1:2:3:3:4:5 with ellipses arc fillstyle pattern 4 title "Echo (33.33%)"

• using 1:2:3:3:4:5对应：x坐标:y坐标:x半轴长度:y半轴长度:起始角度:结束角度
• arc参数指定只绘制椭圆的对应角度区间，从而生成扇形切片
• 调整后，第3列的半径值会被当作绝对长度，和你设定的0.7、1.0完全匹配

内容的提问来源于stack exchange，提问作者Marionette_66