the problem about putting one picture on the left and another on the right

Question

I wish to put two graph together, one is on the left side, the other is one the right side. I use "minipage". However, using the below code, the first graph is on the top of the second graph. May some one help me?

Here is my code:

 \documentclass[tikz]{standalone}
    \usepackage{tikz}
    \usepackage{scalefnt}
    \usetikzlibrary{shapes}
    \begin{document}
    \begin{figure}[htbp]
    \hspace{-4mm}
    \begin{minipage}{0.5\linewidth}]
    \centering
    %\includegraphics[width=2.3in]{image/CompositionalStucture}
    %\input{trans}
    \tikzset{
     block/.style = {circle, draw,align=center,inner sep=0pt},
     line/.style = {draw,->},
     }
    {\scalefont{1}
    \begin{tikzpicture}[node distance=10mm]
    \node[block,minimum size=3mm](s2) {1};
    \node[block,right of =s2,anchor=center,minimum size=2mm] (s3){2};
    \node[block, right of=s2,anchor=center,,minimum size=3mm] (s4) {};

    \path[line] (-0.8,0)-- (s2){};
    \path[line] (s2)-- node[above]{stop}(s4);
    \path[line] (s2) to [out=120,in=40,looseness=5] node[above] {$\Sigma$}(s2);
    \path[line] (s4) to [out=120,in=40,looseness=5]node[above] {$\Sigma$}(s4);
    \end{tikzpicture}
    }
    \caption{Travel Agency Service (\TAS{})}
    \label{fig:TAS}
    \red{2}
    \end{minipage}

    \begin{minipage}{0.5\linewidth}
    \centering
    %\includegraphics[width=2.3in]{image/CompositionalStucture}
    %\input{trans1}
    \tikzset{
     block/.style = {ellipse, draw,align=center,inner sep=0pt},
     line/.style = {draw,->},
     }
    {\scalefont{1}
    \begin{tikzpicture}[node distance=10mm]
    \node[block,minimum size=3.5mm](s1) {(6,1)};
    \node[block,minimum size=3.5mm,below of =s1](s2) {(7,1)};
    \node[block,minimum size=3.5mm,below of = s2](s3) {(22,2)};

    \path[line] (s1)-- node[right]{gc}(s2);
    \path[line] (s2)-- node[right]{TER}(s3);
    \end{tikzpicture}
    }
    \caption{Travel Agency Service (\TAS{})}
    \label{fig:TAS}
    \red{3}
    \end{minipage}
    \end{figure}
    \end{document}

Answer 1

I was not able to compile your example because of undefined control sequences, but I believe the problem is probably caused by the space between the minipages. You have one empty line between the minipages, which means that they will be in separate paragraphs. Even if you delete this line, they will still end up on different lines, because the new-line character between them will insert a space between them, and the line-breaking algorithm will place them on separate lines.

What you want to do is something like this:

\begin{minipage}{0.5\linewidth}
    % some contents here
\end{minipage}% <--- the percent character will "comment out" the new line    
\begin{minipage}{.5\linewidth}
     % some content here
\end{minipage