Line is drawn below x-axis

Question

I want the line to be drawn above the x-axis. Now the line is drawn first and then the x-axis is plotted. I want to reverse it.

\begin{center}
    \begin{tikzpicture}
        \begin{axis}[
            axis lines = center,
            xlabel = \(t\),
            ylabel = {\(\text{Hv}(t)\)},
            ymin=0,
            ymax=1.5,
            every axis plot/.append style={ultra thick},
            tick align=inside
        ]
    \addplot [
        domain=0:5, 
        samples=100, 
        color=red,
    ]
    {1};

    \addplot [
        domain=-5:0, 
        samples=100, 
        color=red,
    ]
    {0};
    \addplot[soldot] coordinates{(0,1)};
    \addplot[holdot] coordinates{(0,0)};
    \end{axis}
\end{tikzpicture}

\end{center}

Thanks in advance

Next time, please post a minimal working example (MWE), like the one used by @Jinwen in their answer. — Rmano, May 27 '22 at 10:45

Rmano · Accepted Answer · 2022-05-27T10:50:15.527

Notice that the axes in pgfplots are normally drawn below the plot traces.

Your problem is brought by the clipping behavior: all plots are clipped to the coordinate areas by default.

If you look closely:

in the horizontal axis, you have the line clipped at y=0; so its thickness is half than expected and you also see half of the line of the axes (which is centered on y=0 too).

You can solve that by using clip=false in the option of the axis environment, but, if you want more fine-grained control over clipping, you can do like this (thanks to @Jinwen answer for the MWE):

\documentclass{article}
\usepackage{mathtools}
\usepackage{pgfplots}\pgfplotsset{compat=newest}
\pgfplotsset{soldot/.style={color=red,only marks,mark=}} \pgfplotsset{holdot/.style={color=red,fill=white,only marks,mark=}}
\begin{document}
\begin{center}
    \begin{tikzpicture}
        \begin{axis}[
            axis lines = center,
            xlabel = (t),
            ylabel = {(\text{Hv}(t))},
            ymin=0,
            ymax=1.5,
            every axis plot/.append style={ultra thick},
            tick align=inside,
            clip mode = individual,
        ]
    \addplot [
        domain=0:5,
        samples=100,
        color=red,
    ]
    {1};

    \addplot [
        domain=-5:0,
        samples=100,
        color=red,
        clip = false,
    ]
    {0};
    \addplot[soldot] coordinates{(0,1)};
    \addplot[holdot] coordinates{(0,0)};
    \end{axis}
\end{tikzpicture}

\end{center}
\end{document}

score 0 · Answer 2 · answered May 27 '22 at 10:20

You can make the axis invisible by setting ymin to be a small negative value (e.g. -0.01). (I don't know your soldot and holdot styles, below is my guess based on this answer.)

\documentclass{article}
\usepackage{mathtools}
\usepackage{pgfplots}
\pgfplotsset{soldot/.style={color=red,only marks,mark=}} \pgfplotsset{holdot/.style={color=red,fill=white,only marks,mark=}}
\begin{document}
\begin{center}
    \begin{tikzpicture}
        \begin{axis}[
            axis lines = center,
            xlabel = (t),
            ylabel = {(\text{Hv}(t))},
            ymin=-.01,
            ymax=1.5,
            every axis plot/.append style={ultra thick},
            tick align=inside
        ]
    \addplot [
        domain=0:5,
        samples=100,
        color=red,
    ]
    {1};

    \addplot [
        domain=-5:0,
        samples=100,
        color=red,
    ]
    {0};
    \addplot[soldot] coordinates{(0,1)};
    \addplot[holdot] coordinates{(0,0)};
    \end{axis}
\end{tikzpicture}

\end{center}
\end{document}

Line is drawn below x-axis

2 Answers2