Tikz 图例条目图像 - 错误的线角

Question

我有一个 ybar tikzpicture，其中有一条水平线来标记阈值。

不幸的是，在图例中这条线并不是水平线，而是一条对角线。

我尝试使用 \addlegendimage 的一些解决方案，但我没能得到一条简单的水平线。

下面你会看到我的图表和 latex 代码。我希望一切都清晰明了。

有人可以帮帮我吗？

如果有任何问题，请随时提问！

提前谢谢您！

马茨

\documentclass{standalone}

\usepackage{pgfplots} 
\pgfplotsset{compat=1.9}

\begin{document}
    
    \begin{tikzpicture}
        \begin{axis}
        [
            title = \Large{\textbf{Überprüfung Alarmauslösung}},
            legend style = {at = {(1,1)}, xshift=0.2cm, yshift=0cm, anchor=north west, nodes=right},
            x tick label style={
                /pgf/number format/1000 sep=},
            ylabel = gemessene Spannung,
            xlabel = Sensor Nr. in 4 Messungen,
            ybar,
            ymin = 0, ymax = 2.5,
            bar width = 7pt,
            xtick={1, 2, 3, 4},
            xmin = 1, xmax = 4,
            enlarge x limits = 0.2,
        ]
        
            
        
            \addplot[blue!50, fill=blue!50]
            coordinates {(1,2.02) (2,2.05) (3,2.08) (4,2.03)};
            \addlegendentry{$Messung~1$}
            
            \addplot[green!50, fill=green!50]
            coordinates {(1,1.8) (2,1.85) (3,1.9) (4,1.82)};
            \addlegendentry{$Messung~2$}
            
            \addplot[red!50, fill=red!50]
            coordinates {(1,1.84) (2,1.87) (3,1.91) (4,1.86)};
            \addlegendentry{$Messung~3$}
            
            \addplot[orange!50, fill=orange!50]
            coordinates {(1,1.89) (2,1.88) (3,1.93) (4,1.86)};
            \addlegendentry{$Messung~4$}
            
            \addplot[red, sharp plot] 
            coordinates {(0,1.743) (1,1.743) (2,1.743) (3,1.743) (4,1.743) (5,1.743)};    
            
            \addlegendimage{no markers, red}
            \addlegendentry{$Alarmschwelle$}
            
            
    
        \end{axis}
    \end{tikzpicture}
    
\end{document}

Answer 1

line legend 2我创建了一个名为下面的新风格

\pgfplotsset{/pgfplots/line legend 2/.style={
legend image code/.code={\draw[thick] (0cm,0cm)--(.25cm,0cm);},},}

/pgfplots/line legend通过修改下面手册中给出的

\pgfplotsset{
/pgfplots/line legend/.style={
legend image code/.code={
\draw [mark repeat=2,mark phase=2,##1]
plot coordinates {
(0cm,0cm)
(0.3cm,0cm)
(0.6cm,0cm)
};
},
},
}

该代码的注释为%<--

\documentclass[border=5mm]{standalone}

\usepackage{pgfplots} 
\pgfplotsset{compat=1.9}
\pgfplotsset{/pgfplots/line legend 2/.style={%<-- new style "line legend 2"
legend image code/.code={\draw[thick] (0cm,0cm)--(.25cm,0cm);},},}
\begin{document}
    
    \begin{tikzpicture}
        \begin{axis}
        [   legend pos=outer north east,
            title = \Large{\textbf{Überprüfung Alarmauslösung}},
%            legend style = {at = {(1,1)}, xshift=0.2cm, yshift=0cm, anchor=north west, nodes=right},
            x tick label style={
                /pgf/number format/1000 sep=},
            ylabel = gemessene Spannung,
            xlabel = Sensor Nr. in 4 Messungen,
            ybar,
            ymin = 0, ymax = 2.5,
            bar width = 7pt,
            xtick={1, 2, 3, 4},
            xmin = 1, xmax = 4,
            enlarge x limits = 0.2,
        ]
        
            \addplot[blue!50, fill=blue!50]
            coordinates {(1,2.02) (2,2.05) (3,2.08) (4,2.03)};
            \addlegendentry{$Messung~1$}
            
            \addplot[green!50, fill=green!50]
            coordinates {(1,1.8) (2,1.85) (3,1.9) (4,1.82)};
            \addlegendentry{$Messung~2$}
            
            \addplot[red!50, fill=red!50]
            coordinates {(1,1.84) (2,1.87) (3,1.91) (4,1.86)};
            \addlegendentry{$Messung~3$}
            
            \addplot[orange!50, fill=orange!50]
            coordinates {(1,1.89) (2,1.88) (3,1.93) (4,1.86)};
            \addlegendentry{$Messung~4$}
            
            \addplot[red,line legend 2,sharp plot] %<-- lien legend 2
            coordinates {(0,1.743) (5,1.743)};    
            
%            \addlegendimage{no markers,red}
            \addlegendentry{$Alarmschwelle$}
            
            
    
        \end{axis}
    \end{tikzpicture}
    
\end{document}