如何访问内部计算的 pgfplots xtick/ytick？

Question

我如何访问ytickpgfplots 内部计算的数据？

\pgfplots@ytick具体来说，仅当在轴环境选项内进行手动定义时，该字段才为非空。包含内部的等效字段是什么ytick？

我想自动重绘一些与 ymajorgrid 绘制的线相同的线，但稍微短一些。

\documentclass{standalone}
\usepackage{verbatim}
\usepackage{pgfplots}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\pgfplotsset{compat = newest}


\makeatletter
\pgfplotsset{
  execute at end axis={ 
        \expandafter\pgfplotsinvokeforeach\expandafter{\pgfplots@ytick}{\draw[gray!50!white,thin] ({axis cs:\pgfplots@data@xmin,#1}) -- ({axis cs:\pgfplots@data@xmax,#1}); }
    },
}
\makeatother

\begin{document}
\begin{tikzpicture}

\begin{axis}[ %ymajorgrids, 
%ytick={5400,5600,5800,6000,6200,6400} %with this line, it works, but I am looking for an automatic alternative
]

\addplot+[thick,mark size=2,error bars/.cd,y dir=both,y explicit ]
coordinates {

(7.846, 5614.5) +- (110., 110.)
(8.096, 5530.) +- (69., 69.)
(8.65, 5442.) +- (57., 57.)
};
\addlegendentry{a}

\addplot+[thick,mark=none]
coordinates {
(7.5, 6319.2)
(9.03, 5996.6)
};
\addlegendentry{b}



\end{axis}
\end{tikzpicture}
\end{document}

Answer 1

我不能说我理解这一切，但它确实有效。

\documentclass{standalone}
\usepackage{verbatim}
\usepackage{pgfplots}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\pgfplotsset{compat = newest}

\begin{document}
\begin{tikzpicture}

\begin{axis}[ %ymajorgrids, 
%ytick={5400,5600,5800,6000,6200,6400} %with this line, it works, but I am looking for an automatic alternative
]

\addplot+[thick,mark size=2,error bars/.cd,y dir=both,y explicit ]
coordinates {

(7.846, 5614.5) +- (110., 110.)
(8.096, 5530.) +- (69., 69.)
(8.65, 5442.) +- (57., 57.)
};
\addlegendentry{a}

\addplot+[thick,mark=none]
coordinates {
(7.5, 6319.2)
(9.03, 5996.6)
};
\addlegendentry{b}

\makeatletter
\pgfplotsextra{
\let\pgfplots@prepared@tick@positions@major@=\pgfplots@prepared@tick@positions@major@y
\pgfplotsonlayer{background}{y grid style}%
\scope
  \pgfplotstransformcoordinatex{\pgfplots@data@xmin}
  \let\xmin=\pgfmathresult
  \pgfplotstransformcoordinatex{\pgfplots@data@xmax}
  \let\xmax=\pgfmathresult
\pgfplots@drawgridlines@INSTALLCLIP@onorientedsurf{y}% no obvious effect
\draw[/pgfplots/every major y grid]%
  \pgfextra
  \pgfplotslistforeach\pgfplots@prepared@tick@positions@major@\as\pgfplots@curgridpos{%
    \expandafter\pgfplots@prepared@tick@pos@unpack\pgfplots@curgridpos
    \pgfpathmoveto{\pgfplotspointonorientedsurfaceab{\pgfplots@tick}{\xmin}}%
    \pgfpathlineto{\pgfplotspointonorientedsurfaceab{\pgfplots@tick}{\xmax}}%
  }%
  \endpgfextra;
\endscope
\endpgfplotsonlayer
}%
\makeatother

\end{axis}
\end{tikzpicture}
\end{document}