pgfplots-向引脚添加偏移量

Question

我正在尝试为量子物理学中的优化参数制作条形图。为了提供更多信息，图表应在条形上方显示这些参数的值。到目前为止，我做到了

\documentclass{minimal}
\usepackage[ngerman]{babel}
\usepackage{pgfplots}
\pgfplotsset{compat=newest}
\begin{document}

\begin{center}
  \begin{tikzpicture}
    \begin{axis}[title={$E_0$ über $n$}, ymax=2.5, yticklabels=]
      \addplot [blue!90!white, fill=blue!50!white, ybar] coordinates {
        ( 1, 1.96556 )
        ( 2, 1.86105 )
        ( 3, 1.93185 )
        ( 4, 2.02568 )
        ( 5, 2.12077 )
        ( 6, 2.21219 )
      };
      \pgfplotsforeachungrouped \x/\y in {1/1.96556, 2/1.86105, 3/1.93185, 4/2.02568, 5/2.12077, 6/2.21219} {
        \edef\temp{\noexpand\node[coordinate, pin={[rotate=90]0:\y}] at (axis cs:\x,\y) {};}\temp
      }
    \end{axis}
  \end{tikzpicture}
\end{center}

\end{document}

此代码输出以下图表

现在我尝试在杆和销钉之间增加一点空间，但我失败了。我尝试++ (axis cs:0,0.1)

\edef\temp{\noexpand\node[coordinate, pin={[rotate=90]0:\y}] at (axis cs:\x,\y) ++ (axis cs:0,0.1) {};}\temp

和++ (axis direction cs:0,0.1)

\edef\temp{\noexpand\node[coordinate, pin={[rotate=90]0:\y}] at (axis cs:\x,\y) ++ (axis direction cs:0,0.1) {};}\temp

两种变体都会出现此错误：

! Package tikz Error: A node must have a (possibly empty) label text.

我也试过pos=0.1

\edef\temp{\noexpand\node[coordinate, pin={[rotate=90]0:\y},pos=0.1] at (axis cs:\x,\y) {};}\temp

编译成功，但输出如下

提前谢谢您，maeru。

Answer 1

我将尽可能坚持pgfplots使用节点样式。您可以将引脚选项传递给nodes near coords以及许多其他选项（颜色、线条样式等），如下所示：

\documentclass{standalone}
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
\begin{axis}[title={$E_0$ über $n$}, ymax=2.5, yticklabels=,
nodes near coords={\pgfmathprintnumber[precision=4]\pgfplotspointmeta},
nodes near coords align={
     shift={(0,1.5cm)},
     rotate=90,
     pin={[pin distance = 0.75cm,
          pin edge={thick,double=yellow}]180:},
     text=red
}
]
  \addplot [blue!90!white, fill=blue!50!white, ybar] coordinates {
    ( 1, 1.96556 )
    ( 2, 1.86105 )
    ( 3, 1.93185 )
    ( 4, 2.02568 )
    ( 5, 2.12077 )
    ( 6, 2.21219 )
  };

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

Answer 2

制作帽子的一种方法是使用 tikz 的calc库来调整放置大头针的坐标：

($(axis cs:\x,\y)+(0.0cm,0.1cm)$)

代码：

\documentclass{article}
\usepackage[ngerman]{babel}
\usepackage{pgfplots}
\pgfplotsset{compat=newest}
\usetikzlibrary{calc}
\begin{document}

\begin{center}
  \begin{tikzpicture}
    \begin{axis}[title={$E_0$ über $n$}, ymax=2.5, yticklabels=]
      \addplot [blue!90!white, fill=blue!50!white, ybar] coordinates {
        ( 1, 1.96556 )
        ( 2, 1.86105 )
        ( 3, 1.93185 )
        ( 4, 2.02568 )
        ( 5, 2.12077 )
        ( 6, 2.21219 )
      };
      \pgfplotsforeachungrouped \x/\y in {1/1.96556, 2/1.86105, 3/1.93185, 4/2.02568, 5/2.12077, 6/2.21219} {
        \edef\temp{\noexpand\node[coordinate, pin={[rotate=90]0:\y}] at ($(axis cs:\x,\y)+(0.0cm,0.1cm)$) {};}\temp
      }
    \end{axis}
  \end{tikzpicture}
\end{center}

\end{document}

Answer 3

我的解决方案

这个问题有很多很好的答案，但我选择了阻力最小的路径，只是添加了shift={(0,0.1cm)}

\edef\temp{\noexpand\node[coordinate,shift={(0,0.1cm)},pin = {[rotate=90]0:\y}] at (axis cs:\x,\y) { };}