使用 tikzset 创建的自定义图例标记

Question

例子：

\documentclass{article}
\usepackage{pgfplots}
\usepackage{xcolor}


% Define TikZ styles for interpolation points and values
\newcommand{\interpolationPointStyle}{%
    \tikzset{interpolation point/.style={circle, inner sep=1.5pt, fill=black}}
}

\begin{document}

\begin{tikzpicture}

\interpolationPointStyle

\begin{axis}[
    xlabel={$x$},
    ylabel={$y$},
    ymin=0,
    xtick=\empty,
    axis background/.style={fill=white},
clip=false,
]

% Define array of tick positions
\def\myxticks{3, 4, 5}
% Loop over tick positions and draw interpolation points
\foreach \tick in \myxticks {
    \edef\tmp{\noexpand\node[interpolation point] at (axis cs:\tick,0) {};}
    \tmp
}
% Curve 1
\addplot[color=red, mark=none, smooth] coordinates {
    (3, 0.5)
    (4, 0.6)
    (5, 0.4)
};
\addlegendentry{Curve 1}

% Interpolation points
\addlegendimage{interpolation point}
\addlegendentry{Interpolation Points}

\end{axis}
\end{tikzpicture}

\end{document}

产生输出

问题：

我想将我在 x 轴上绘制的插值点符号显示在图例中。我以为将其放在图例图像中就可以了，但结果却出现了一条直线。

必须纠正什么？

Answer 1

这是我对你的代码的修改：

\documentclass{article}
\usepackage{pgfplots}
\usepackage{tikz}
\usepackage{xcolor}

% Define TikZ styles for interpolation points and values
\newcommand{\interpolationPointStyle}{%
    \tikzset{interpolation point/.style={circle, inner sep=1.5pt, fill=black}}
}

\begin{document}

\begin{tikzpicture}

\interpolationPointStyle

\begin{axis}[
    xlabel={$x$},
    ylabel={$y$},
    ymin=0,
    xtick=\empty,
    axis background/.style={fill=white},
    clip=false,
    legend style={at={(0.5,-0.2)}, anchor=north, legend columns=-1}
]

% Define array of tick positions
\def\myxticks{3, 4, 5}
% Loop over tick positions and draw interpolation points
\foreach \tick in \myxticks {
    \edef\tmp{\noexpand\node[interpolation point] at (axis cs:\tick,0) {};}
    \tmp
}
% Curve 1
\addplot[color=red, mark=none, smooth] coordinates {
    (3, 0.5)
    (4, 0.6)
    (5, 0.4)
};
\addlegendentry{Curve 1}

% Manually create legend entry for interpolation points
\addlegendimage{only marks, mark=*, mark options={fill=black, scale=0.8}}
\addlegendentry{Interpolation Points}

\end{axis}
\end{tikzpicture}

\end{document}

这应该产生如下输出：

我擅自将图例放在了底部。对此我深表歉意。我个人认为您遇到问题是因为\addlegendimage没有直接使用 TikZ 绘图命令，因此无法识别插值点的 TikZ 样式。

但这只是我的理论，我不是 100% 确定。

Answer 2

我找到了解决问题的方法：

\documentclass{article}
\usepackage{pgfplots}
\usepackage{xcolor}


% Define TikZ styles for interpolation points
\newcommand{\interpolationPointStyle}{%
    \tikzset{interpolation point/.style={circle, inner sep=1.5pt, fill=black}}
}

% Define custom legend styles for interpolation points 
\pgfplotsset{
    interpolation point legend/.style={
        legend image code/.code={
            \node[interpolation point] at (0.3cm,0cm) {};
        }
    },
}

\begin{document}

\begin{tikzpicture}

\interpolationPointStyle

\begin{axis}[
    xlabel={$x$},
    ylabel={$y$},
    ymin=0,
    xtick=\empty,
    axis background/.style={fill=white},
clip=false,
]

% Define array of tick positions
\def\myxticks{3, 4, 5}
% Loop over tick positions and draw interpolation points
\foreach \tick in \myxticks {
    \edef\tmp{\noexpand\node[interpolation point] at (axis cs:\tick,0) {};}
    \tmp
}
% Curve 1
\addplot[color=red, mark=none, smooth] coordinates {
    (3, 0.5)
    (4, 0.6)
    (5, 0.4)
};
\addlegendentry{Curve 1}

\addlegendimage{interpolation point legend}
\addlegendentry{Interpolation Points}

\end{axis}
\end{tikzpicture}

\end{document}

输出：