pgfplots：y 轴箭头朝下

Question

我怎样才能使 y 轴箭头位于轴的另一端并指向下方？

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{makecell}
\setcellgapes{5pt}
\usepackage{booktabs}
\usepackage{amsmath,amssymb,amsfonts,systeme,mathtools} 
\usepackage{chemfig}
\usepackage[version=3]{mhchem}
\usepackage{pgfplots}
\usepackage{float}

\begin{document}

\begin{figure}[H]
\centering
\begin{tikzpicture}
  \begin{axis}[
  legend pos=outer north east,
  legend cell align={left},
  grid, grid style=dashed,
  xmax=1.1,xmin=0,
  ymin=-1.2,ymax=0,
  ytick={-1.1,-1,-0.9,-0.8,-0.7,-0.6,-0.5,-0.4,-0.3,-0.2,-0.1},
  xtick={0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9,1},
  extra y ticks={0},            % <---
  extra x ticks={0},            % <---
  axis lines = middle,
  set layers,                   % <---
  xlabel={$x_2$},ylabel={$V_m$}, 
  x label style={at={(1,1)},right},
  y label style={at={(0,0)},below},
               ]
  \addplot[mark=*,scatter,only marks]
    coordinates {
    (0.0281,-0.115)(0.0435,-0.157)(0.0587,-0.262)(0.0896,-0.359)(0.1180,-0.500)(0.1524,-0.631)(0.3107,-0.894)(1,0)
    };
    \end{axis}
    \begin{axis}[
    legend pos=outer north east,
    legend cell align={left},
    hide axis,
    ymin=-1.2,ymax=0,
    xmax=1.1,xmin=0,
    domain=0:1,
    samples=2000,
    set layers,
    ]
   \addplot [cyan,smooth,thick,dashed] {4.3292*x*x - 4.3116*x - 0.0153};
   \end{axis}
\end{tikzpicture}
\end{figure}

\end{document}

你能帮助我吗？

先感谢您

Answer 1

y axis line style={stealth-}只需在选项末尾添加即可 axis。

参见pgfplots手册 p271 §4.9。轴描述（在 v1.15 中）

\documentclass{article}
\usepackage{pgfplots}
\pgfplotsset{compat=newest}
\begin{document}

\begin{tikzpicture}
  \begin{axis}[
  legend pos=outer north east,
  legend cell align={left},
  grid, grid style=dashed,
  xmax=1.1,xmin=0,
  ymin=-1.2,ymax=0,
  ytick={-1.1,-1,-0.9,-0.8,-0.7,-0.6,-0.5,-0.4,-0.3,-0.2,-0.1},
  xtick={0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9,1},
  extra y ticks={0},            % <---
  extra x ticks={0},            % <---
  axis lines = middle,
  set layers,                   % <---
  xlabel={$x_2$},ylabel={$V_m$}, 
  x label style={at={(1,1)},right},
  y label style={at={(0,-1)},above},
  y axis line style={stealth-},   % <====== right here !
               ]
  \addplot[mark=*,scatter,only marks]
    coordinates {
    (0.0281,-0.115)(0.0435,-0.157)(0.0587,-0.262)(0.0896,-0.359)(0.1180,-0.500)(0.1524,-0.631)(0.3107,-0.894)(1,0)
    };
    \end{axis}
    \begin{axis}[
    legend pos=outer north east,
    legend cell align={left},
    hide axis,
    ymin=-1.2,ymax=0,
    xmax=1.1,xmin=0,
    domain=0:1,
    samples=2000,
    set layers,
    ]
   \addplot [cyan,smooth,thick,dashed] {4.3292*x*x - 4.3116*x - 0.0153};
   \end{axis}
\end{tikzpicture}
\end{document}