在条形图上绘制趋势线

Question

对于下面的 MWE：

\documentclass{report}
\usepackage[left=2.5cm,right=2cm,top=2cm,bottom=2cm]{geometry}
\usepackage[T1]{fontenc}
\usepackage{pgfplots}


\begin{document}

\begin{figure}[H]
\centering
\begin{tikzpicture}
\begin{axis}[xmode=normal,ymode=log,
ybar,
scaled y ticks = true,
grid=both,
minor y tick num=5,
ylabel={Elapsed Time (in hours)},
xlabel={Number of Constraints},
width=1*\textwidth,
height=9cm,
bar width=3.5pt,
symbolic x coords={3,4,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35
},
xtick=data,
ymin=0
%nodes near coords,
%nodes near coords align={vertical},
]

\addplot [fill=red]
coordinates {(3,38.9575) (4,166.897) (6,53.63835) (7,39.6594) (8,82.1631) (9,40.22045) (10,37.2932) (11,131.62625) (12,472.6995) (13,149.837) (14,113.445) (15,108.474) (16,155.24455) (17,95.41392) (18,186.819) (19,153.383) (20,313.361) (21,180.1305) (22,401.3485) (23,1621.092) (24,1929.3) (25,899.283) (26,726.926) (27,1624.4) (28,870.348) (29,979.472) (30,869.418) (31,274.83) (32,1945.87) (33,1359.09) (34,891.24) (35,1625.31)     };
    \end{axis}
\end{tikzpicture}
\caption{The Elapsed Time vs. The Number of Constraints for the Halving Method}
\end{figure}

\end{document}

如何在条形图顶部绘制趋势线？趋势线指的是触及图表上每个条形顶点的线。

Answer 1

您可以将数据放入表中以便重复使用（我通过几个查找/替换操作做到了这一点）。我看不出如何symbolic x coords从第一列生成（虽然我记得这样做过）。我还添加了smooth和line join选项以使行不那么碍事。

\documentclass{report}
\usepackage[left=2.5cm,right=2cm,top=2cm,bottom=2cm]{geometry}
\usepackage[T1]{fontenc}
\usepackage{pgfplots}
\pgfplotstableread{
3 38.9575
4 166.897
6 53.63835
7 39.6594
8 82.1631 
9 40.22045 
10 37.2932 
11 131.62625 
12 472.6995 
13 149.837 
14 113.445 
15 108.474 
16 155.24455
17 95.41392
18 186.819 
19 153.383
20 313.361
21 180.1305 
22 401.3485 
23 1621.092
24 1929.3
25 899.283 
26 726.926 
27 1624.4 
28 870.348 
29 979.472
30 869.418
31 274.83 
32 1945.87
33 1359.09
34 891.24
35 1625.31
}\mytable

\begin{document}

\begin{figure}[H]
\centering
\begin{tikzpicture}
\begin{axis}[xmode=normal,ymode=log,
scaled y ticks = true,
grid=both,
minor y tick num=5,
ylabel={Elapsed Time (in hours)},
xlabel={Number of Constraints},
width=1*\textwidth,
height=9cm,
symbolic x coords={3,4,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35},
xtick=data,
ymin=0
]

\addplot [fill=red,ybar,bar width=3.5pt] table[header=false] {\mytable};
\addplot [ultra thick,orange,line join=round,smooth] table[header=false] {\mytable};

    \end{axis}
\end{tikzpicture}
\caption{The Elapsed Time vs. The Number of Constraints for the Halving Method}
\end{figure}

\end{document}