'Smarter' axis arrows in pgfplot

Question

For any common x>0, y>0 function the standard axis arrow locations in a pgfplot are great

Unfortunately, for more negative functions (domain or range), the arrows are a bit funny (red = what I want).

It does seem possible to manually set the arrows right as in pgfplots: y axis arrow pointing down

However what would be fantastic is if it were possible to have te plot use the right arrows automaticly!

I'm thinking some sort of logic such as:

• If x-axis goes >0 use right arrow
• If x-axis goes <0 use left arrow
• If y-axis goes >0 use top arrow
• If y-axis goes <0 use bottom arrow

However I have no clue how this might be done, would anyone be willing to help?

MWE

\documentclass{article}

\usepackage{pgfplots}
\usetikzlibrary{arrows.meta}

\pgfplotsset{
    no marks,axis lines=middle,
    inner axis line style={-{Latex[length=4mm]}}
}

\begin{document}

\begin{center}
    \begin{tikzpicture}
        \begin{axis}[domain=0:1]
            \addplot+{x};
        \end{axis}
    \end{tikzpicture}
\end{center}

\end{document}

Answer 1

This does what you suggest, I think. The iaxis style looks whether the origin is left/right/above/below of the axis boundaries, and adds the arrows accordingly.

\documentclass{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.16}
\usetikzlibrary{arrows.meta,calc}

\pgfplotsset{no marks,
    iaxis/.style={,axis lines=middle,
    inner axis line style={-},clip mode=individual,execute at end axis={
    \path[tips=proper] let \p1=($(rel axis cs:1,1)-(axis cs:0,0)$),
     \p2=($(axis cs:0,0)-(rel axis cs:0,0)$)
     in %\pgfextra{\typeout{\x1,\x2,\y1,\y2}}
     \ifdim\x1>0pt
      (axis cs:0,0) edge[-{Latex[length=4mm]}] ({rel axis cs:1,0} |- {axis cs:0,0})
     \fi
     \ifdim\x2>0pt
      (axis cs:0,0) edge[-{Latex[length=4mm]}] ({rel axis cs:0,0} |- {axis cs:0,0})
     \fi
     \ifdim\y1>0pt
      (axis cs:0,0) edge[-{Latex[length=4mm]}] ({rel axis cs:0,1} -| {axis cs:0,0})
     \fi
     \ifdim\y2>0pt
      (axis cs:0,0) edge[-{Latex[length=4mm]}] ({rel axis cs:0,0} -| {axis cs:0,0})
     \fi;
    }},
    every axis/.append style=iaxis
}

\begin{document}
\begin{tabular}{cc}
\begin{tikzpicture}
    \begin{axis}[domain=0:1]
        \addplot+{x};
    \end{axis}
\end{tikzpicture} &
\begin{tikzpicture}
    \begin{axis}[domain=0:1]
        \addplot+{-x};
    \end{axis}
\end{tikzpicture}\\
\begin{tikzpicture}
    \begin{axis}[domain=-1:0]
        \addplot+{x};
    \end{axis}
\end{tikzpicture} &
\begin{tikzpicture}
    \begin{axis}[domain=-1:0]
        \addplot+{-x};
    \end{axis}
\end{tikzpicture}\\
\begin{tikzpicture}
    \begin{axis}[domain=-1:1]
        \addplot+{-x};
    \end{axis}
\end{tikzpicture}
\end{tabular}
\end{document}

Or with overshooting arrows (which alter the dimensions of the axis objects).

\documentclass{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.16}
\usetikzlibrary{arrows.meta,calc}

\pgfplotsset{no marks,
    iaxis/.style={axis lines=middle,
    inner axis line style={-},clip mode=individual,execute at end axis={
    \path[tips=proper] let \p1=($(rel axis cs:1,1)-(axis cs:0,0)$),
     \p2=($(axis cs:0,0)-(rel axis cs:0,0)$)
     in %\pgfextra{\typeout{\x1,\x2,\y1,\y2}}
     \ifdim\x1>0pt
      (axis cs:0,0) edge[-{Latex[length=4mm]}] 
      ($({rel axis cs:1,0} |- {axis cs:0,0})+($(4mm,0)-(0,0)$)$)
     \fi
     \ifdim\x2>0pt
      (axis cs:0,0) edge[-{Latex[length=4mm]}] 
      ($({rel axis cs:0,0} |- {axis cs:0,0})+($(-4mm,0)-(0,0)$)$)
     \fi
     \ifdim\y1>0pt
      (axis cs:0,0) edge[-{Latex[length=4mm]}] 
      ($({rel axis cs:0,1} -| {axis cs:0,0})+($(0,4mm)-(0,0)$)$)
     \fi
     \ifdim\y2>0pt
      (axis cs:0,0) edge[-{Latex[length=4mm]}] 
      ($({rel axis cs:0,0} -| {axis cs:0,0})+($(0,-4mm)-(0,0)$)$)
     \fi;
    }},
    every axis/.append style=iaxis
}

\begin{document}
\begin{tabular}{cc}
\begin{tikzpicture}
    \begin{axis}[domain=0:1]
        \addplot+{x};
    \end{axis}
\end{tikzpicture} &
\begin{tikzpicture}
    \begin{axis}[domain=0:1]
        \addplot+{-x};
    \end{axis}
\end{tikzpicture}\\
\begin{tikzpicture}
    \begin{axis}[domain=-1:0]
        \addplot+{x};
    \end{axis}
\end{tikzpicture} &
\begin{tikzpicture}
    \begin{axis}[domain=-1:0]
        \addplot+{-x};
    \end{axis}
\end{tikzpicture}\\
\begin{tikzpicture}
    \begin{axis}[domain=-1:1]
        \addplot+{-x};
    \end{axis}
\end{tikzpicture}
\end{tabular}
\end{document}