我想在下图所示的相图中，沿着轨迹绘制“隐形”箭头来代替“0”标签。我决定使用 Pgfplots 的轮廓功能来绘制轨迹。到目前为止，我设法将标签的内部间距设置为零，但我无法弄清楚如何更改标签文本。你有什么想法吗？
这是我用来生成图表的代码：
\documentclass{standalone}
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
\begin{axis}[
title={Phase portrait of Van der Pol oscillator.},
domain=-2:2,
xmin=-2,
xmax=2,
ymin=-2,
ymax=2,
view={0}{90},
axis background/.style={fill=white}
]
\addplot3[
contour prepared =
{
contour label style = {
inner sep = 0pt
},
draw color = black,
label distance = 140pt,
handler/.style = /tikz/smooth
}
] table {
1 1 0
1.06298 0.924071 0
1.12034 0.837528 0
1.1715 0.742761 0
1.21604 0.642327 0
1.2537 0.53874 0
1.28439 0.434294 0
1.30815 0.330936 0
1.32515 0.230198 0
1.33561 0.133173 0
1.33981 0.0405447 0
1.33807 -0.0473723 0
1.33071 -0.130566 0
1.31803 -0.209266 0
1.30032 -0.283883 0
1.27781 -0.354957 0
1.25071 -0.423121 0
1.21919 -0.489065 0
1.18336 -0.553523 0
1.14327 -0.617253 0
1.09894 -0.681037 0
1.05031 -0.745674 0
0.997309 -0.811985 0
0.939765 -0.880811 0
0.877471 -0.953012 0
0.81016 -1.02946 0
0.737503 -1.11104 0
0.659117 -1.19857 0
0.574566 -1.2928 0
0.483372 -1.39432 0
0.385033 -1.50335 0
0.279056 -1.61961 0
0.165004 -1.742 0
0.0425688 -1.86824 0
-0.0883296 -1.99446 0
-0.227417 -2.1148 0
-0.37392 -2.22123 0
-0.526427 -2.30376 0
-0.68279 -2.35129 0
-0.84013 -2.35325 0
-0.994979 -2.30182 0
-1.14358 -2.19409 0
-1.28228 -2.03341 0
-1.40797 -1.82915 0
-1.5184 -1.59496 0
-1.61235 -1.34614 0
-1.68956 -1.09692 0
-1.75062 -0.858681 0
-1.79667 -0.639141 0
-1.82921 -0.442463 0
-1.84984 -0.269927 0
-1.86016 -0.120777 0
-1.86162 0.00698576 0
-1.85553 0.115975 0
-1.84301 0.208983 0
-1.82497 0.288714 0
-1.80219 0.357639 0
-1.77525 0.417936 0
-1.74466 0.471483 0
-1.71076 0.519882 0
-1.67385 0.56449 0
-1.6341 0.606463 0
-1.59164 0.646794 0
-1.54654 0.686352 0
-1.49881 0.725909 0
-1.44841 0.766178 0
-1.39527 0.807829 0
-1.33925 0.85152 0
-1.2802 0.89791 0
-1.21788 0.947684 0
-1.15205 1.00156 0
-1.0824 1.06031 0
-1.00855 1.12475 0
-0.930078 1.19577 0
-0.846509 1.27428 0
-0.757294 1.36121 0
-0.661824 1.45744 0
-0.559443 1.56366 0
-0.449463 1.68024 0
-0.331198 1.80687 0
-0.204031 1.94227 0
-0.0675019 2.08357 0
0.0785556 2.22577 0
0.233841 2.3611 0
0.397387 2.47881 0
0.567366 2.5655 0
0.740977 2.60659 0
0.914493 2.58894 0
1.08351 2.50416 0
1.24344 2.35155 0
1.39009 2.13913 0
1.52018 1.88231 0
1.6317 1.60044 0
1.72397 1.31283 0
1.79745 1.03554 0
1.85344 0.779751 0
1.89372 0.551697 0
1.92029 0.353461 0
1.93511 0.184222 0
1.94001 0.0414127 0
1.93657 -0.0783631 0
};
\addplot3[
color=black!30!white,
quiver={
u={y},
v={0 - x + y * (1 - x^2)},
scale arrows=0.1
},
-stealth,
samples=20
]{0};
\end{axis}
\end{tikzpicture}
\end{document}
感谢您的帮助！
答案1
在这种情况下，我不会使用contour，而是使用正常的图，并使用放置箭头decoration：
\documentclass[border=5mm]{standalone}
\usepackage{pgfplots}
\usetikzlibrary{decorations.markings}
\begin{document}
\begin{tikzpicture}
\begin{axis}[
title={Phase portrait of Van der Pol oscillator.},
domain=-2:2,
xmin=-2,
xmax=2,
ymin=-2,
ymax=2,
view={0}{90},
axis background/.style={fill=white}
]
\addplot3[
color=black!30!white,
quiver={
u={y},
v={0 - x + y * (1 - x^2)},
scale arrows=0.1
},
-stealth,
samples=20
]{0};
\addplot3[decoration={
markings,
mark=between positions 0.1 and 1 step 8em with {\arrow [scale=1.5]{stealth}}
}, postaction=decorate] table {
1 1 0
1.06298 0.924071 0
1.12034 0.837528 0
1.1715 0.742761 0
1.21604 0.642327 0
1.2537 0.53874 0
1.28439 0.434294 0
1.30815 0.330936 0
1.32515 0.230198 0
1.33561 0.133173 0
1.33981 0.0405447 0
1.33807 -0.0473723 0
1.33071 -0.130566 0
1.31803 -0.209266 0
1.30032 -0.283883 0
1.27781 -0.354957 0
1.25071 -0.423121 0
1.21919 -0.489065 0
1.18336 -0.553523 0
1.14327 -0.617253 0
1.09894 -0.681037 0
1.05031 -0.745674 0
0.997309 -0.811985 0
0.939765 -0.880811 0
0.877471 -0.953012 0
0.81016 -1.02946 0
0.737503 -1.11104 0
0.659117 -1.19857 0
0.574566 -1.2928 0
0.483372 -1.39432 0
0.385033 -1.50335 0
0.279056 -1.61961 0
0.165004 -1.742 0
0.0425688 -1.86824 0
-0.0883296 -1.99446 0
-0.227417 -2.1148 0
-0.37392 -2.22123 0
-0.526427 -2.30376 0
-0.68279 -2.35129 0
-0.84013 -2.35325 0
-0.994979 -2.30182 0
-1.14358 -2.19409 0
-1.28228 -2.03341 0
-1.40797 -1.82915 0
-1.5184 -1.59496 0
-1.61235 -1.34614 0
-1.68956 -1.09692 0
-1.75062 -0.858681 0
-1.79667 -0.639141 0
-1.82921 -0.442463 0
-1.84984 -0.269927 0
-1.86016 -0.120777 0
-1.86162 0.00698576 0
-1.85553 0.115975 0
-1.84301 0.208983 0
-1.82497 0.288714 0
-1.80219 0.357639 0
-1.77525 0.417936 0
-1.74466 0.471483 0
-1.71076 0.519882 0
-1.67385 0.56449 0
-1.6341 0.606463 0
-1.59164 0.646794 0
-1.54654 0.686352 0
-1.49881 0.725909 0
-1.44841 0.766178 0
-1.39527 0.807829 0
-1.33925 0.85152 0
-1.2802 0.89791 0
-1.21788 0.947684 0
-1.15205 1.00156 0
-1.0824 1.06031 0
-1.00855 1.12475 0
-0.930078 1.19577 0
-0.846509 1.27428 0
-0.757294 1.36121 0
-0.661824 1.45744 0
-0.559443 1.56366 0
-0.449463 1.68024 0
-0.331198 1.80687 0
-0.204031 1.94227 0
-0.0675019 2.08357 0
0.0785556 2.22577 0
0.233841 2.3611 0
0.397387 2.47881 0
0.567366 2.5655 0
0.740977 2.60659 0
0.914493 2.58894 0
1.08351 2.50416 0
1.24344 2.35155 0
1.39009 2.13913 0
1.52018 1.88231 0
1.6317 1.60044 0
1.72397 1.31283 0
1.79745 1.03554 0
1.85344 0.779751 0
1.89372 0.551697 0
1.92029 0.353461 0
1.93511 0.184222 0
1.94001 0.0414127 0
1.93657 -0.0783631 0
};
\end{axis}
\end{tikzpicture}
\end{document}