pgfplots 散点图图例上的错误

Question

我在使用 pgfkeys 的散点图中遇到了图例问题。图例中半正方形符号的颜色与图中定义的颜色不同，如下图 MWE 所示。

我该如何纠正这个问题？

\documentclass{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.16} 

\begin{document}

    \begin{tikzpicture} 
    \pgfplotsset{
            height=6cm, 
            scatter/classes={%
                    a={mark=square,draw=blue},%
                    b={mark=triangle,draw=red},%
                    c={mark=o,draw=orange},
                    d={mark=diamond,draw=green},
                    e={mark=pentagon,draw=magenta},
                    f={mark=halfsquare*,cyan,draw=cyan}
                    },
        }
        \tikzset{every mark/.append style={scale=2},
                }
        \def\ec{2cm}
        % this is the leftmost y axis
        \begin{axis}[        
            xmin=0,xmax=1,%--- CF
            xshift=0,%-- CF
            width=1.8cm,
            hide x axis,
            axis y line*=left,
            ymin=25, ymax=27.5,
            ytick distance=0.5,
            title={$V_{max}$ (V)},
            legend style={at={(3,0.5)},anchor=west}
        ]
        \addplot+ [
            only marks,
            %mark=ball,
            scatter,% enable scatter
            scatter src=explicit symbolic,% the "color data"
                ]
            table[meta=label] {PlotV.dat};
            \legend{a,b,c,d,e,f}
        \end{axis}


     \end{tikzpicture}

\end{document}

Answer 1

这是一个没有问题的版本。更干净的方法可能是重写该标记的代码，pgflibraryplotmarks.code.tex但至少以下是一种解决方法。遗憾的是我不得不编造数据。

\documentclass{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.16} 
\begin{filecontents*}{PlotV.dat}
x y label 
0.1 0.15 a 
0.45 0.27 b 
0.02 0.17 c 
0.06 0.1 d
0.9 0.5 e 
0.5 0.3 f 
0.85 0.52 a 
0.12 0.05 b 
0.73 0.45 c 
0.53 0.25 d 
0.76 0.5 e 
0.55 0.32 f
\end{filecontents*}

\begin{document}

    \begin{tikzpicture} 
    \pgfplotsset{
            height=6cm, 
            scatter/classes={%
                    a={mark=square,draw=blue},%
                    b={mark=triangle,draw=red},%
                    c={mark=o,draw=orange},%
                    d={mark=diamond,draw=green},%
                    e={mark=pentagon,draw=magenta},%
                    f={mark=halfsquare*,cyan,mark options={cyan,scale=2}}%
                    },
        }
        \tikzset{every mark/.append style={scale=2},
                }
        \def\ec{2cm}
        % this is the leftmost y axis
        \begin{axis}[        
            xmin=0,xmax=1,%--- CF
            xshift=0,%-- CF
            width=1.8cm,
            hide x axis,
            axis y line*=left,
            %ymin=25, ymax=27.5,
            ytick distance=0.5,
            title={$V_\mathrm{max}$ (V)},
            legend style={at={(3,0.5)},anchor=west}
        ]
        \addplot+ [
            only marks,
            %mark=ball,
            scatter,% enable scatter
            scatter src=explicit symbolic,% the "color data"
                ]
            table[meta=label] {PlotV.dat};
            \legend{a,b,c,d,e,f}
        \end{axis}


     \end{tikzpicture}

\end{document}