Tell pgfplots to put tick labels between tick marks

Question

Is it possible to tell pgfplots to put tick labels between the tick marks instead of at the tick marks?

MWE:

\documentclass[margin=5pt]{standalone}

\usepackage{tikz}
\usepackage{pgfplots}

\begin{document}

    \begin{tikzpicture}

        \begin{axis}[
            width=5in,
            height=3in,
            axis lines=middle,
            scaled ticks=false,
            xtick=\empty,
            xmin=0,
            xmax=3,
            extra x ticks={0,1,2,3},
            extra x tick labels={low,high,med},
        ]

        \addplot [mark=*,draw] coordinates {(0.5,2) (1.5,4) (2.5,3)};

        \end{axis}
    \end{tikzpicture}

\end{document}

Result:

I can do it manually by adding

xticklabel style = {xshift=1.9cm,align=center},

but this seems unsatisfying, unreliable, and requires too much trial and error.

Answer 1

How about

\documentclass[tikz,border=3.14mm]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.16}
\begin{document}

    \begin{tikzpicture}

        \begin{axis}[
            width=5in,
            height=3in,
            axis lines=middle,
            scaled ticks=false,
            xtick=\empty,
            xmin=0,
            xmax=3,
            xtick={0,1,2,3},
            xticklabel=\empty,
            extra x ticks={0.5,1.5,2.5},
            extra x tick labels={low,high,med},
            extra x tick style={major tick length=0pt}
        ]

        \addplot [mark=*,draw] coordinates {(0.5,2) (1.5,4) (2.5,3)};

        \end{axis}
    \end{tikzpicture}

\end{document}

Answer 2

x tick label as interval is just what you want, but the problem is with axis lines=middle the tick position 0 is ignored by default and no tick is generated, so there are only two tick intervals instead of three, and so the first label ("low") goes missing.

My solution is to use extra x ticks to supply the missing interval and label but keep the extra ticks from showing with the help of style.

\documentclass[margin=5pt]{standalone}

\usepackage{tikz}
\usepackage{pgfplots}
\pgfplotsset{compat=1.18}

\begin{document}

    \begin{tikzpicture}

        \begin{axis}[
            width=5in,
            height=3in,
            axis lines=middle,
            scaled ticks=false,
            xmin=0,
            xmax=3,
            x tick label as interval,
            xtick={1,2,3},
            xticklabels={high,med},
            % first label would be missing w/o the lines below
            extra x ticks={0.1, 0.9},
            extra x tick labels={low},
            extra x tick style={
                tick style={draw=none}
            },
        ]

        \addplot [mark=*,draw] coordinates {(0.5,2) (1.5,4) (2.5,3)};

        \end{axis}
    \end{tikzpicture}

\end{document}