# Different Directed graph

I need to do a graph similar to the one in the picture above but I don't know how to do the horizontal lines without the arrow, or the vertical arrow. The best I could do is the following:

\documentclass{amsart}
\usepackage{tikz}
\begin{document}
\begin{center}
\begin{tikzpicture}
\node (p1) at ( 0, 0) {};
\node (p2) at ( 1, -0.2) {i};
\node (p3) at ( 3,0) {};
\node (p4) at ( 0,1) {};
\node (p5) at ( 2,1.2) {n+j};
\node (p6) at ( 3,1) {};
\begin{scope}[every path/.style={->}]
\draw (p1) -- (p3);
\draw (p4) -- (p6);
\draw (p2) -- (p5);
\end{scope}
\end{tikzpicture}
\end{center}
\end{document}


Output

• Mmmm... I'm guessing this has to do with style={->}. :) – Werner Sep 30 '14 at 0:26
• – Peter Grill Sep 30 '14 at 0:45
• Why not put i and n+j in math mode? ($i$ and $n+j$) – user10274 Sep 30 '14 at 13:28

Is this the desired result:

## Notes:

• If you don't want arrow heads on the end of lines, either change the style to every path/.style={-} or simply eliminate that option as I have done below. Lines do not get arrow heads be default.
• The style of the arrow that you desire is -latex. So, just add that option when needed (as is the case for the orange line).
• Added shorten <= and shorten >= to extend the orange line. Alternatively you could manully select points that are on the line.
• The calc library was used to compute the midway coordinates with which the vertical black line was drawn.
• I made the node labels to be in math mode by adding the $. • Colors added to make it easier to know which drawing command is doing what. ## Code: \documentclass{amsart} \usepackage{tikz} \usetikzlibrary{calc} \begin{document} \begin{center} \begin{tikzpicture}[thick] \node (p1) at ( 0, 0) {}; \node (p2) at ( 1, -0.2) {$i$}; \node (p3) at ( 3,0) {}; \node (p4) at ( 0,1) {}; \node (p5) at ( 2,1.2) {$n+j$}; \node (p6) at ( 3,1) {}; \coordinate (p1MidwayP3) at ($(p1)!0.5!(p3)$); \coordinate (p4MidwayP6) at ($(p4)!0.5!(p6)$); \begin{scope}%[every path/.style={-}] \draw [red] (p1) -- (p3); \draw [blue] (p4) -- (p6); \draw [orange, shorten <=-0.08cm, shorten >=-0.10cm, -latex](p2) -- (p5); \draw (p1MidwayP3) -- (p4MidwayP6); \end{scope} \end{tikzpicture} \end{center} \end{document}  A PSTricks solution, combined with xfp: \documentclass{article} \usepackage{pstricks-add} \usepackage{xfp} \begin{document} \def\Horizontal{5} % length of the horizontal line segments \def\Vertical{3} % length of the vertical line segment \def\Indent{0.5} % indentation of the arrow from both sides \begin{pspicture}(0,-0.4)(\Horizontal,\fpeval{\Vertical+0.45}) \psline(0,0)(\Horizontal,0) \psline(0,\Vertical)(\Horizontal,\Vertical) \psline(\fpeval{\Horizontal/2},0)(\fpeval{\Horizontal/2},\Vertical) \psline{->}(\Indent,0)(\fpeval{\Horizontal-\Indent},\Vertical) \uput[270](\Indent,0){$i$} \uput[90](\fpeval{\Horizontal-\Indent},\Vertical){$n+j\$}
\end{pspicture}

\end{document}


All you have to do is choose the values of \Horizontal, \Vertical, and \Indent and the drawing will be adjusted accordingly.