Tikz 图例无法添加？

Question

tikz我以为我可以通过为图片添加图例\addlegendentry{...}。但是，只要我取消注释该命令，编译器就会抱怨缺少}。但是当我再次注释这些行时，它就可以正常工作了。有人可以给我提示一下，为什么图例不起作用？

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows, intersections}
\usepackage{pgfplots}
 \pgfplotsset{compat=newest}
  \pgfplotsset{plot coordinates/math parser=false}
%from matlab2tikz
   \newlength\figureheight
   \newlength\figurewidth 


\begin{document}
Sample plot with out legend?

\begin{figure}       
        \setlength\figureheight{2cm}
        \setlength\figurewidth{2.7cm} 
               { 


\begin{tikzpicture}[font=\tiny]
\begin{axis}[%
width=\figurewidth,
height=\figureheight,
scale only axis,
xmin=1,
xmax=20,
ymin=0,
ymax=2,
title={Sample time series}, 
legend style={draw=black,fill=white,legend cell align=left}
]
\addplot [color=blue,solid,forget plot]
  table[row sep=crcr]{1 1\\
2       1\\
3       1\\
4       1\\
5       1\\
6       1\\
7       1\\
8       1\\
9       1\\
10      2\\
11      1\\
12      1.5\\
13      0\\
14      1\\
15      1\\
16      1\\
17      1\\
18      1\\
19      1\\
20      1\\
};
\addplot [color=green,dashed ,forget plot]
  table[row sep=crcr]{8 0\\
  8 2\\
  10 2\\
  10 0\\
};
%\addlegendentry{Window size=2};
\addplot [color=violet,densely dotted ,forget plot]
  table[row sep=crcr]{10.5 0\\
  10.5 2\\
  15.5 2\\
  15.5 0\\
};
%\addlegendentry{Window size=5};
\end{axis}
\end{tikzpicture}%

                    }

\end{figure} 
\end{document}

Answer 1

不要forget plot用于您想要添加图例的图表（forget plot适用于不应记住图例条目也不应考虑循环列表的图表）：

\documentclass[twoside]{article}
\usepackage{pgfplots}

\newlength\figurewidth
\setlength\figurewidth{6cm}
\newlength\figureheight
\setlength\figureheight{6cm}

\begin{document}

\begin{tikzpicture}[font=\tiny]
\begin{axis}[%
width=\figurewidth,
height=\figureheight,
scale only axis,
xmin=1,
xmax=20,
ymin=0,
ymax=2,
title={Sample time series}, 
legend style={draw=black,fill=white,legend cell align=left}
]
\addplot [color=blue,solid,forget plot]
  table[row sep=crcr]{1 1\\
2       1\\
3       1\\
4       1\\
5       1\\
6       1\\
7       1\\
8       1\\
9       1\\
10      2\\
11      1\\
12      1.5\\
13      0\\
14      1\\
15      1\\
16      1\\
17      1\\
18      1\\
19      1\\
20      1\\
};
\addplot [color=green,dashed ]
  table[row sep=crcr]{8 0\\
  8 2\\
  10 2\\
  10 0\\
};
\addlegendentry{Window size=2}
\addplot [color=violet,densely dotted ]
  table[row sep=crcr]{10.5 0\\
  10.5 2\\
  15.5 2\\
  15.5 0\\
};
\addlegendentry{Window size=5}
\end{axis}
\end{tikzpicture}%

\end{document}