pgfplots 文档中的注释

Question

我需要修改这段代码的哪些部分才能获得简单的注释？

\begin{tikzpicture}
\begin{axis}[
xtick={45,46,...,55},
ytick={0,0.1,...,1},
width=18cm,
height=10cm,
grid=major,
minor x tick num=9,
%minor y tick num={1},
ymin=0,
ymax=1,
xmin=45,
xmax=55,
]
\addplot[mark=none, blue, line width=1.5pt] coordinates {(45,0)(47,0.1)(49,0.35)(51,0.775)(53,0.875)(55,1)};

\addplot[mark=none, dashed, red] coordinates {(0,0.5)(49.7,0.5)(49.7,0.5)(49.7,0)};
\node at (axis cs:49.7,-0.15){Me};

\addplot[mark=none, dashed, red] coordinates {(0,0.25)(48.2,0.25)(48.2,0.25)(48.2,0)};
\node at (axis cs:48.2,-0.15){$Q_1$};

\addplot[mark=none, dashed, red] coordinates {(0,0.75)(50.9,0.75)(50.9,0.75)(50.9,0)};
\node at (axis cs:50.9,-0.15){$Q_3$};

\end{axis}
\end{tikzpicture}

Answer 1

正如 Torbjørn 在在问题下方评论解决您的问题的“快速解决方案”是简单地使用clip mode=individual，但“您的”方式 - 在我看来 - 不是添加注释的理想解决方案。

这里我介绍另一种使用的方法extra ticks。有关更多详细信息，请查看代码中的注释。

\documentclass[border=5pt]{standalone}
\usepackage{pgfplots}
    \pgfplotsset{
        % use `compat' level 1.11 or higher so you don't need to add
        % `axis cs:' to each TikZ coordinate
        compat=1.11,
    }
\begin{document}
    \begin{tikzpicture}
        \begin{axis}[
%            % not needed, because this is the default with this scales
%            xtick={45,46,...,55},
            % and instead of applying the `ytick`s just give the "distance"
            ytick distance=0.1,
            %
            width=18cm,
            height=10cm,
            grid=major,
            minor x tick num=9,
            ymin=0,
            ymax=1,
            xmin=45,
            xmax=55,
            %
            % if you don't want to draw markers (anywhere), disable it globally
            no markers,
            % where do you want to draw the extra labels ...
            extra x ticks={48.2,49.7,50.9},
            extra x tick style={
                % and what should the labels state
                xticklabels={$Q_1$,Me,$Q_3$},
                % adjust the style so it fits your needs ...
                % you don't want to draw (extra) grid lines there
                grid=none,
                % you also don't want to draw extra ticks there
                major tick length=0pt,
                % and the labels should be moved below the "normal" ticklabels
                xticklabel style={
                    yshift=-3ex,
                },
                % to align the labels on the same baseline
                % (for your current labels that doesn't change anything,
                %  but if you change e.g. "Me" to "me" and "$Q_3$" to
                %  "${Q_3^2}^2$", you will see the difference, if you comment
                %  the next line)
                typeset ticklabels with strut,
            },
        ]
        \addplot[mark=none, blue, line width=1.5pt] coordinates {
            (45,0)(47,0.1)(49,0.35)(51,0.775)(53,0.875)(55,1)
        };

        % you only need _3_ coordinates to plot the dashed lines
        % and so you don't need to adapt the "lower" values when changing the
        % axis limits, just use them directly in the coordinates
        \addplot [dashed, red] coordinates {
            (\pgfkeysvalueof{/pgfplots/xmin},0.25)
            (48.2,0.25)
            (48.2,\pgfkeysvalueof{/pgfplots/ymin})
        };
        % but you can also do it with _2_ coordinates using TikZ's `\draw' command
        \draw [dashed, red]
            (\pgfkeysvalueof{/pgfplots/xmin},0.5) -| (49.7,\pgfkeysvalueof{/pgfplots/ymin})
        ;
        \draw [dashed, red]
            (\pgfkeysvalueof{/pgfplots/xmin},0.75) -| (50.9,\pgfkeysvalueof{/pgfplots/ymin})
        ;
        \end{axis}
    \end{tikzpicture}
\end{document}