如何在gnuplot中获得一个中间箭头？

Question

我想在gnuplot中画一个箭头,箭头出现在箭头中间而不是极端.尝试中间头选项但似乎不起作用.

这是我用来创建下面图像的脚本,

set style arrow 1 front head filled size screen 0.008,6 lt 1 lw 1
set arrow from  0.4750,-0.3592 to 1.05767,0.4179 as 1

Answer 1

正如安德拉斯已经指出的那样:没有选择来做到这一点.但是,您可以创建一个为您构建两个箭头的函数,并计算中间点.该函数middlearrow将包含两个箭头定义的字符串组合在一起,然后必须使用以下内容处理eval:

set style arrow 1 front head filled size screen 0.03,15 lt 1 lw 1
middlearrow(from_x, from_y, to_x, to_y) = \
        sprintf('set arrow from %f,%f to %f,%f as 1 nohead;', 0.5*(from_x + to_x), 0.5*(from_y + to_y), to_x, to_y).\
        sprintf('set arrow from %f,%f to %f,%f as 1', from_x, from_y, 0.5*(from_x + to_x), 0.5*(from_y + to_y)) 

eval(middlearrow(0.1,0.1,0.9,0.9))

set xrange [0:1]
set yrange [0:1]

plot 0

结果与4.6.4: