pgfplots-同一图例行中有更多符号（具有相同的图例文本）

Question

我有以下 PGFPlots（小样本）。

\documentclass[11pt, a4paper, twoside]{scrreprt} % [11pt, parskip]{scrartcl} 
\usepackage[utf8]{inputenc}

\usepackage[colorlinks = true, citecolor=black, filecolor=black, linkcolor=black, urlcolor=black, linktocpage=true]{hyperref}
\usepackage{tikz}       % Zeichnungen
\usepackage{pgfplots}   % Diagramme

\begin{document}
\begin{tikzpicture}
\begin{axis}[
scatter/classes={a={blue},b={mark=triangle*,blue},c={mark=square*,blue}},
every x tick scale label/.style={at={(xticklabel cs:1)},anchor=south west},
every axis plot/.append style={mark=none} , 
legend pos=north east,
legend style={draw=none, fill=none},
]
\addplot [scatter, only marks, scatter src=explicit symbolic] 
    coordinates{
    (1,1) [a]
    (1,2) [b]
    (1,3) [c]
    (2,2) [a]
    };
\addplot [color=red]
coordinates{
    (1,1)
    (2,2)
};
\legend{~,~,Data,Fit}
\end{axis}
\end{tikzpicture}
\end{document}

我现在想要以下样式的图例（一行）：
标准标记，三角形，正方形数据

我更新了示例，因为我得到了一些新信息，我还必须将 Fit 放入数据中。在图片中，您可以找到我希望图例看起来是什么样子的示例。

Answer 1

人们总是可以使用\addlegendentry和将图例拼凑在一起\addlegendimage。然后就可以想出任何legend image code自己喜欢的东西。这是一个例子，当然可以改进。为了找到标记的合适坐标，我line legend在手册中查找了代码。

\documentclass[11pt, a4paper, twoside]{scrreprt} % [11pt, parskip]{scrartcl} 
\usepackage[utf8]{inputenc}

\usepackage[colorlinks = true, citecolor=black, filecolor=black, linkcolor=black, urlcolor=black, linktocpage=true]{hyperref}
\usepackage{tikz}       % Zeichnungen
\usepackage{pgfplots}   % Diagramme

\pgfplotsset{%
my legend/.style={legend image code/.code={%
\node[##1,anchor=west] at (0cm,0cm){\pgfuseplotmark{*}};
\node[##1] at (0.3cm,0cm){\pgfuseplotmark{triangle*}};
\node[##1,anchor=east] at (0.6cm,0cm){\pgfuseplotmark{square*}};
}},%
}

\begin{document}
\begin{tikzpicture}
\begin{axis}[
scatter/classes={a={blue},b={mark=triangle*,blue},c={mark=square*,blue}},
every x tick scale label/.style={at={(xticklabel cs:1)},anchor=south west},
every axis plot/.append style={mark=none} , 
legend pos=north east,
legend style={draw=none, fill=none},
]
\addlegendimage{my legend,blue}
\addlegendentry{Data}
\addlegendimage{line legend,red,line width=1pt}
\addlegendentry{Fit}

\addplot [scatter, only marks, scatter src=explicit symbolic] 
    coordinates{
    (1,1) [a]
    (1,2) [b]
    (1,3) [c]
    (2,2) [a]
    };
\addplot [color=red]
coordinates{
    (1,1)
    (2,2)
};
\end{axis}
\end{tikzpicture}
\end{document}