考慮到我之前的問題，我有一些 MATLAB 等值線圖，其原始顏色圖parula由以下rgb資料定義：
MATLAB 色彩圖（parula）
如何使用 PGFPlots 重現下面所示的原始 MATLAB 色條，並使其水平跨越三個子圖下方的空間（知道色條的最小值為 ，300最大值為1600）？
\RequirePackage{luatex85}
\documentclass{article}
\usepackage{pgfplots,caption,subcaption,showframe,siunitx}
\usepgfplotslibrary{groupplots}
\pgfplotsset{compat=newest}
\begin{document}
\begin{figure}
\centering
\begin{tikzpicture}
\begin{groupplot}[
group style={
group name=G,
group size=3 by 1,
y descriptions at=edge left,
horizontal sep=20pt % adjust as needed
},
enlargelimits=false,
width=0.28\textwidth-width("300"),
height=0.25\textheight,
scale only axis, axis on top , grid=both,
]
\nextgroupplot
\addplot graphics [xmin=0, xmax=50, ymin=0, ymax=150] {example-image-a};
\nextgroupplot
\addplot graphics [xmin=0, xmax=50, ymin=0, ymax=150] {example-image-b};
\nextgroupplot
\addplot graphics [xmin=0, xmax=50, ymin=0, ymax=150] {example-image-c};
\end{groupplot}
\end{tikzpicture}
\end{figure}
\end{document}
答案1
那你的意思是像下面這樣嗎？
（因為我認為您將修改顯示的色條，使其與您之前問題中的色條相對應，也許還有中的提示https://tex.stackexchange.com/a/336647/95441有幫助。
% used PGFPlots v1.14
\RequirePackage{luatex85}
\documentclass{article}
\usepackage{pgfplots}
\usepgfplotslibrary{groupplots}
\pgfplotsset{
% define the colormap
colormap={parula}{
rgb=(0.208100000000000,0.166300000000000,0.529200000000000)
rgb=(0.211623809523810,0.189780952380952,0.577676190476191)
rgb=(0.212252380952381,0.213771428571429,0.626971428571429)
rgb=(0.208100000000000,0.238600000000000,0.677085714285714)
rgb=(0.195904761904762,0.264457142857143,0.727900000000000)
rgb=(0.170728571428571,0.291938095238095,0.779247619047619)
rgb=(0.125271428571429,0.324242857142857,0.830271428571429)
rgb=(0.0591333333333334,0.359833333333333,0.868333333333333)
rgb=(0.0116952380952381,0.387509523809524,0.881957142857143)
rgb=(0.00595714285714286,0.408614285714286,0.882842857142857)
rgb=(0.0165142857142857,0.426600000000000,0.878633333333333)
rgb=(0.0328523809523810,0.443042857142857,0.871957142857143)
rgb=(0.0498142857142857,0.458571428571429,0.864057142857143)
rgb=(0.0629333333333333,0.473690476190476,0.855438095238095)
rgb=(0.0722666666666667,0.488666666666667,0.846700000000000)
rgb=(0.0779428571428572,0.503985714285714,0.838371428571429)
rgb=(0.0793476190476190,0.520023809523810,0.831180952380952)
rgb=(0.0749428571428571,0.537542857142857,0.826271428571429)
rgb=(0.0640571428571428,0.556985714285714,0.823957142857143)
rgb=(0.0487714285714286,0.577223809523810,0.822828571428572)
rgb=(0.0343428571428572,0.596580952380952,0.819852380952381)
rgb=(0.0265000000000000,0.613700000000000,0.813500000000000)
rgb=(0.0238904761904762,0.628661904761905,0.803761904761905)
rgb=(0.0230904761904762,0.641785714285714,0.791266666666667)
rgb=(0.0227714285714286,0.653485714285714,0.776757142857143)
rgb=(0.0266619047619048,0.664195238095238,0.760719047619048)
rgb=(0.0383714285714286,0.674271428571429,0.743552380952381)
rgb=(0.0589714285714286,0.683757142857143,0.725385714285714)
rgb=(0.0843000000000000,0.692833333333333,0.706166666666667)
rgb=(0.113295238095238,0.701500000000000,0.685857142857143)
rgb=(0.145271428571429,0.709757142857143,0.664628571428572)
rgb=(0.180133333333333,0.717657142857143,0.642433333333333)
rgb=(0.217828571428571,0.725042857142857,0.619261904761905)
rgb=(0.258642857142857,0.731714285714286,0.595428571428571)
rgb=(0.302171428571429,0.737604761904762,0.571185714285714)
rgb=(0.348166666666667,0.742433333333333,0.547266666666667)
rgb=(0.395257142857143,0.745900000000000,0.524442857142857)
rgb=(0.442009523809524,0.748080952380952,0.503314285714286)
rgb=(0.487123809523809,0.749061904761905,0.483976190476191)
rgb=(0.530028571428571,0.749114285714286,0.466114285714286)
rgb=(0.570857142857143,0.748519047619048,0.449390476190476)
rgb=(0.609852380952381,0.747314285714286,0.433685714285714)
rgb=(0.647300000000000,0.745600000000000,0.418800000000000)
rgb=(0.683419047619048,0.743476190476191,0.404433333333333)
rgb=(0.718409523809524,0.741133333333333,0.390476190476190)
rgb=(0.752485714285714,0.738400000000000,0.376814285714286)
rgb=(0.785842857142857,0.735566666666667,0.363271428571429)
rgb=(0.818504761904762,0.732733333333333,0.349790476190476)
rgb=(0.850657142857143,0.729900000000000,0.336028571428571)
rgb=(0.882433333333333,0.727433333333333,0.321700000000000)
rgb=(0.913933333333333,0.725785714285714,0.306276190476191)
rgb=(0.944957142857143,0.726114285714286,0.288642857142857)
rgb=(0.973895238095238,0.731395238095238,0.266647619047619)
rgb=(0.993771428571429,0.745457142857143,0.240347619047619)
rgb=(0.999042857142857,0.765314285714286,0.216414285714286)
rgb=(0.995533333333333,0.786057142857143,0.196652380952381)
rgb=(0.988000000000000,0.806600000000000,0.179366666666667)
rgb=(0.978857142857143,0.827142857142857,0.163314285714286)
rgb=(0.969700000000000,0.848138095238095,0.147452380952381)
rgb=(0.962585714285714,0.870514285714286,0.130900000000000)
rgb=(0.958871428571429,0.894900000000000,0.113242857142857)
rgb=(0.959823809523810,0.921833333333333,0.0948380952380953)
rgb=(0.966100000000000,0.951442857142857,0.0755333333333333)
rgb=(0.976300000000000,0.983100000000000,0.0538000000000000)
},
}
\begin{document}
\begin{tikzpicture}
\begin{groupplot}[
group style={
group name=G,
group size=3 by 1,
y descriptions at=edge left,
horizontal sep=20pt % adjust as needed
},
enlargelimits=false,
% !!! I don't know what the part `width("300")' is doing exactly !!!
width=0.28\textwidth-width("300"),
height=0.25\textheight,
scale only axis,
axis on top,
grid=both,
]
% add the colorbar to the first groupplot
\nextgroupplot [
% it should be horizontal ...
colorbar horizontal,
% ... and sampled
colorbar sampled,
% define the style of the colorbar
colorbar style={
% it should be positioned at ...
at=(G c1r1.below south west),
% ... with the anchor ...
anchor=north west,
% ... with the same width as the axis parts of the groupplots,
% i.e. 3 times the width of a single groupplot plus two times
% the width of the horizontal sep of the groupplots, ...
parent axis width=3*(0.28\textwidth-width("300")) + 2*20pt,
% ... and the start and end points ...
point meta min=300,
point meta max=1600,
% ... and the number of samples should be identical to the
% number of colors in the colormap
samples={
\pgfplotscolormapsizeof{%
\pgfkeysvalueof{/pgfplots/colormap name}%
}+1
},
},
]
\addplot graphics [xmin=0, xmax=50, ymin=0, ymax=150] {example-image-a};
\nextgroupplot
\addplot graphics [xmin=0, xmax=50, ymin=0, ymax=150] {example-image-b};
\nextgroupplot
\addplot graphics [xmin=0, xmax=50, ymin=0, ymax=150] {example-image-c};
\end{groupplot}
% % for debugging purposes only
% \draw [red,very thin]
% (G c1r1.south west) -- +(0,-1cm)
% (G c3r1.south east) -- +(0,-1cm)
% ;
\end{tikzpicture}
\end{document}
