我正在绘制一个相当不寻常的条形图来显示一项小型调查的结果。图表的轴在负域和正域中延伸。但是，没有零，所有值都是正的。这听起来相当复杂，所以这里有一张图片：
看到实际值会很好。 PGFPlots 手册第 4.4.4 节建议nodes near coords, nodes near coords align = {horizontal}在这些情况下使用。结果如下：
这看起来不错，但值显然是错误的。为了让条形图忘记实际上没有零值，我更改了绘图样式中的 x 刻度并减去 1。因此，条形旁边显示的值是 PGFPlots 的坐标，也是我输入的唯一坐标。
现在，有两个选择：在编译期间计算它|x|+1（第一张图片）或明确添加正确的值（第二张图片）：
这两个选项都以不同的方式弄乱了布局，我不知道如何正确定位节点。这是生成所示图表的 MWE 代码：
\documentclass[11pt]{article}
\usepackage[utf8]{inputenc}
\usepackage{pgfplots}
\usepackage{floatrow}
\usepackage{subfigure}
\pgfplotsset{TestBar/.style={% Overall settings
width = 0.75\textwidth,
line width=1pt,
tick style={line width=0.8pt},
xmin = -8, xmax = 8,
xtick = {-8,-6,-4,-2, 0, 2, 4, 6, 8},
xticklabels = { 9, 7, 5, 3, 1, 3, 5, 7, 9},
xmajorgrids = true,
minor x tick num = 1,
tick align = outside,
xtick pos = left, ytick pos = left,
xbar,
height = 3cm,
enlarge y limits = 0.5, ytick = {1,2},
yticklabels = {C2, C1}}
}
\pgfplotsset{TestBarY/.style={% Draw y-Axis without anything
width = 0.75\textwidth,
height = 3cm,
line width = 1pt,
xmin = -8, xmax = 8,
xmajorgrids = false,
xtick = \empty, ytick = \empty,
no markers,
minor x tick num = 1,
axis y line* = center}
}
\pgfplotsset{TextA/.style={}}% Show no values
\pgfplotsset{TextB/.style={% Show value as given in the coordinates.
nodes near coords,
nodes near coords align = {horizontal}}
}
\pgfplotsset{TextC/.style={% Calculate value in point-meta.
nodes near coords,
nodes near coords align={horizontal},
point meta = {abs(x)+1}}
}
\pgfplotsset{TextD/.style={% Caption explicitly added in point-meta.
nodes near coords,
nodes near coords align={horizontal},
point meta = explicit symbolic}
}
\begin{document}
\begin{figure}[htb]
\subfigure[TextA: no text.]{
\begin{tikzpicture}
\begin{axis}[TestBar]
\addplot[TextA] coordinates { (2.555,1) (-1.279,2) };
\end{axis}
\begin{axis}[TestBarY]\addplot coordinates {(0,0)};\end{axis}
\end{tikzpicture}}\
\subfigure[TextB: node-text from coordinates.]{
\begin{tikzpicture}
\begin{axis}[TestBar]
\addplot[TextB] coordinates { (2.555,1) (-1.279,2) };
\end{axis}
\begin{axis}[TestBarY]\addplot coordinates {(0,0)};\end{axis}
\end{tikzpicture}}\
\subfigure[TextC: node-text calculated in \emph{point meta} as abs(x)+1.]{
\begin{tikzpicture}
\begin{axis}[TestBar]
\addplot[TextC] coordinates { (2.555,1) (-1.279,2) };
\end{axis}
\begin{axis}[TestBarY]\addplot coordinates {(0,0)};\end{axis}
\end{tikzpicture}}\
\subfigure[TextD: node-text explicitly added to \emph{point meta}.]{
\begin{tikzpicture}
\begin{axis}[TestBar]
\addplot[TextD] coordinates { (2.555,1) [3.56] (-1.279,2) [2.28] };
\end{axis}
\begin{axis}[TestBarY]\addplot coordinates {(0,0)};\end{axis}
\end{tikzpicture}}
\end{figure}
\end{document}
答案1
对齐horizontal选项通过查看值的符号来确定将标签放在条形图的左侧还是右侧meta。通过将其转换为绝对值，所有标签最终都会位于右侧。实现您要执行的操作的一种方法是仅在将meta值打印在标签中时转换它。您可以使用
nodes near coords={
\pgfkeys{/pgf/fpu=true}
\pgfmathparse{abs(\pgfplotspointmeta)+1}
\pgfmathprintnumber{\pgfmathresult}
}
fpu首先需要打开库，因为该meta值已转换为浮点表示。然后您可以进行计算，最后使用 打印数字\pgfmathprintnumber。
额外提示：在 x=0 处绘制一条线，你不必使用一个全新的轴。关键
before end axis/.code={
\draw ({rel axis cs:0,0}-|{axis cs:0,0}) -- ({rel axis cs:0,1}-|{axis cs:0,0});
}
将绘制一条从 x=0 处的图底部开始到顶部的线，无论轴限制如何。
完整代码如下：
\documentclass[11pt]{article}
\usepackage{pgfplots}
\pgfplotsset{
TestBar/.style={% Overall settings
width = 0.75\textwidth,
line width=1pt,
tick style={line width=0.8pt},
xmin = -8, xmax = 8,
xtick = {-8,-6,-4,-2, 0, 2, 4, 6, 8},
xticklabels = { 9, 7, 5, 3, 1, 3, 5, 7, 9},
xmajorgrids = true,
minor x tick num = 1,
tick align = outside,
xtick pos = left, ytick pos = left,
xbar,
height = 3cm,
enlarge y limits = 0.5, ytick = {1,2},
yticklabels = {C2, C1},
nodes near coords={
\pgfkeys{/pgf/fpu=true}%
\pgfmathparse{abs(\pgfplotspointmeta)+1}%
\pgfmathprintnumber{\pgfmathresult}
},
nodes near coords align = {horizontal},
before end axis/.code={
\draw ({rel axis cs:0,0}-|{axis cs:0,0}) -- ({rel axis cs:0,1}-|{axis cs:0,0});
}
}
}
\begin{document}
\begin{tikzpicture}
\begin{axis}[TestBar]
\addplot [] coordinates { (2.555,1) (-1.279,2) };
\end{axis}
\end{tikzpicture}
\end{document}