How to draw an arc in Tikz that has gaps specifically placed in it

Question

I was wondering how I could draw an arc in Tikz that has small gaps in it in a simple way, like this:

Here is working example:

\documentclass{article}

\usepackage{tikz}

\begin{document}

\begin{figure}
\centering
\begin{tikzpicture}
\draw (6,2.5) arc (0:180:4cm and 1cm);
\end{tikzpicture}
\end{figure}

\end{document}

The gaps need not be of different lengths.

Much appreciated,

Alex

Welcome to TeX.SX! Would using \draw[loosely dashed] or some suitably-defined custom dash pattern work? — Paul Gessler, Mar 23 '15 at 11:40

score 10 · Answer 1 · answered Mar 23 '15 at 11:41

10

According to the pgfmanual section 15.3.2 Graphic Parameters: Dash Pattern, you have several possibilities:

\documentclass[tikz,border=10pt]{standalone}

\begin{document}
\begin{tikzpicture}[very thick]
\draw[dashed] (6,2.5) arc (0:180:4cm and 1cm);
\end{tikzpicture}

\begin{tikzpicture}[very thick]
\draw[loosely dashed] (6,2.5) arc (0:180:4cm and 1cm);
\end{tikzpicture}

\begin{tikzpicture}[very thick]
\draw[dash pattern=on 6mm off 7mm] (6,2.5) arc (0:180:4cm and 1cm);
\end{tikzpicture}
\end{document}

The result:

enter image description here

answered Mar 23 '15 at 11:41

Claudio Fiandrino

63,575

For a solution to the well know issue at the two ends of the line, please refer to Can TikZ dashed lines emulate PSTricks dashed lines?. – Claudio Fiandrino Mar 23 '15 at 11:45
Thank you for your answer. However, salviati's solution solves the problem by allowing more specific placement of the gaps I need in the arc. – Alex Mar 23 '15 at 11:56
@Alex: You're welcome and remember that you can always select to accept the answer that fully satisfies your needs. – Claudio Fiandrino Mar 23 '15 at 12:05

score 7 · Accepted Answer · answered Mar 23 '15 at 11:41

7

Try the dash pattern style on your path with on and off pairs:

\documentclass[tikz]{standalone}
\begin{document}
\begin{tikzpicture}
\draw [dash pattern=on 1.5cm off 1cm on 1cm off 1cm on 1cm off .5cm on 1cm off .5cm]
    (6,2.5) arc (0:180:4cm and 1cm);
\end{tikzpicture}
\end{document}

result

answered Mar 23 '15 at 11:41

salviati

423

The on-and-off pairs technique solves my problem. Thank you very much! – Alex Mar 23 '15 at 11:53

Franck Pastor · Answer 3 · 2015-03-23T15:24:37.873

It seems that the dash pattern key option of tikz has been borrowed from MetaPost: the syntax is exactly the same. I couldn't let this pass without reacting, so for the sake of justice here is Salviati's example translated in tikz's original language :-)

beginfig(1);
    draw halfcircle xscaled (8cm) yscaled (2cm) 
        dashed dashpattern(on 1.5cm off 1cm on 1cm off 1cm on 1cm off .5cm on 1cm off .5cm);
endfig;
end.

enter image description here

How to draw an arc in Tikz that has gaps specifically placed in it

3 Answers3