这个问题源自发布的问题这里。我怎样才能让绘图在阴影区域之间的区域中显示为红色，如下所示：
原始代码如下：
\documentclass{book}
\usepackage{tikz}
\usepackage{pgfplots}
\usepgfplotslibrary{fillbetween}
\pgfplotsset{compat=1.10}
\pgfplotsset{minor grid style={dotted,gray!50}}
\pgfplotsset{major grid style={gray!50!black}}
\newcommand{\datafile}{Noise2.dat}
\begin{filecontents*}{\datafile}
Freq Orig Filt
100.000, -79.374, -119.392
101.801, -79.858, -119.321
103.634, -78.587, -117.497
105.501, -79.077, -117.437
107.401, -78.735, -116.547
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498.511, -85.588, -102.942
507.489, -84.458, -102.006
516.628, -84.730, -102.477
525.933, -85.516, -103.467
535.405, -83.314, -101.475
545.047, -85.678, -104.054
10000.000, -117.204, -288.714
\end{filecontents*}
% https://tex.stackexchange.com/questions/164991/pgfplots-how-to-fill-bounded-area-under-a-curve-using-addplot-and-fill?rq=1
\begin{document}
\begin{figure}
\centering
\begin{tikzpicture}[every plot/.append style={very thick}]
\begin{semilogxaxis}[width=14cm,height=10cm,
grid = both,
every major grid/.style={gray, opacity=0.7},
ymin = -130,
ymax = -70,
title = {},
xlabel={\emph{Offset Frequency (Hz)}},
ylabel={\emph{Noise}},
extra y ticks = {-70}]
\addplot+ [smooth,blue,name path=A] table[mark = none, x index=0,y index=1,col sep=comma] {\datafile};
\addplot+[draw=none,name path=B, domain=500:1000, mark=none] {-130};
\addplot+[gray, draw=red, thick, fill opacity=0.4] fill between[of=A and B,soft clip={domain=500:1000}];
\end{semilogxaxis}
\end{tikzpicture}
\caption{Response.}
\end{figure}
\end{document}
答案1
我认为最简单的方法是使用intersection segments。基本上，我画一条沿着阴影区域的长路径，得到与图的交点并在其上画红色。
我还用这种新方法替换了以前绘制阴影区域边框的命令，这样图底部就不会出现红线。
细节：
输出
代码
\documentclass{book}
\usepackage{tikz}
\usepackage{pgfplots}
\usepgfplotslibrary{fillbetween}
\pgfplotsset{compat=1.10}
\pgfplotsset{minor grid style={dotted,gray!50}}
\pgfplotsset{major grid style={gray!50!black}}
\newcommand{\datafile}{Noise.dat}
\begin{filecontents*}{\datafile}
Freq Orig Filt
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101.801, -79.858, -119.321
103.634, -78.587, -117.497
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\end{filecontents*}
% http://tex.stackexchange.com/questions/164991/pgfplots-how-to-fill-bounded-area-under-a-curve-using-addplot-and-fill?rq=1
\begin{document}
\begin{figure}
\centering
\begin{tikzpicture}[every plot/.append style={very thick}]
\begin{semilogxaxis}[width=14cm,height=10cm,
grid = both,
every major grid/.style={gray, opacity=0.7},
ymin = -130,
ymax = -70,
title = {},
xlabel={\emph{Offset Frequency (Hz)}},
ylabel={\emph{Noise}},
extra y ticks = {-70}]
\addplot+ [smooth,blue,name path=A] table[mark = none, x index=0,y index=1,col sep=comma] {\datafile};
\addplot+[draw=none,name path=B, domain=500:1000, mark=none] {-130};
\addplot+[gray, fill opacity=0.4] fill between[of=A and B,soft clip={domain=500:1000}];
\path[name path=cut] (axis cs: 500,\pgfkeysvalueof{/pgfplots/ymin}) --
(axis cs: 500,\pgfkeysvalueof{/pgfplots/ymax}) --
(axis cs: 1000,\pgfkeysvalueof{/pgfplots/ymax}) --
(axis cs: 1000,\pgfkeysvalueof{/pgfplots/ymin});
\draw[red,very thick,
intersection segments={
of=A and cut,
sequence={R1--L2--R0}
}];
\end{semilogxaxis}
\end{tikzpicture}
\caption{Response.}
\end{figure}
\end{document}