# Labeling TIKZ graph with greek letters

I am not very experienced in TIKZ but I have made a few graphs such as this.

When I try to change the names of the labels to greek letters I run into errors. Is there a way to modify my code where it'll change the labels to alpha, beta, etc?

Here is the code:

\documentclass{beamer}

\usepackage{tikz}

\usepackage{verbatim}
\usetikzlibrary{arrows,shapes}

\begin{document}
\pgfdeclarelayer{background}
\pgfsetlayers{background,main}

\tikzstyle{vertex}=[circle,fill=black!25,minimum size=14pt,inner sep=0pt]
\tikzstyle{selected vertex} = [vertex, fill=red!24]
\tikzstyle{edge} = [draw,thick,-]
\tikzstyle{weight} = [font=\small]
\tikzstyle{selected edge} = [draw,line width=5pt,-,red!50]
\tikzstyle{ignored edge} = [draw,line width=5pt,-,black!20]

%Start of graph
\begin{tikzpicture}[scale=.7, auto,swap]
\foreach \pos/\name in {{(0,0)/a},{(2,0)/b},{(3,2)/c},{(2,4)/d},{(0,4)/e},
{(-1,2)/f},{(-1,-1)/1},{(-2,-2)/2},{(3,-1)/3},{(4,-2)/4},{(4,2)/5},
{(5,2)/6},{(-2,2)/7},{(-3,2)/8},{(-1,5)/9},{(-2,6)/10},{(3,5)/11},
{(4,6)/12}}
\node[vertex] (\name) at \pos {$\name$};
% Connect vertices with edges
\foreach \source/ \dest /\weight in {a/b/, b/c/, c/d/, d/e/,
e/f/,f/a/,a/1/,1/2/,b/3/,3/4/,c/5/,5/6/,f/7/,7/8/,e/9/,9/10/,d/11/,11/12/}
\path[edge] (\source) -- node[weight] {$\weight$} (\dest);

\end{tikzpicture}
\end{document}

• Welcome to TeX.SX! Please don't post code fragments. Instead, put your fragments into a complete compilable document that shows the problem. – Alan Munn Aug 16 '17 at 19:14
• \foreach \pos/\name in {{(0,0)/\alpha},{(2,0)/\beta},{(3,2)/\gamma},...} \node[vertex] (\name) at \pos {$\name$}; ? – Zarko Aug 16 '17 at 19:17

You could split the first loop in two, introducing a third loop variable for the first part, representing the node text (\alpha, \beta, etc.).

\documentclass{beamer}

\usepackage{tikz}

\usepackage{verbatim}
\usetikzlibrary{arrows,shapes}

\begin{document}
\begin{frame}
\pgfdeclarelayer{background}
\pgfsetlayers{background,main}

\tikzset{
vertex/.style={circle,fill=black!25,minimum size=14pt,inner sep=0pt},
selected vertex/.style={vertex, fill=red!24},
edge/.style={draw,thick,-},
weight/.style={font=\small},
selected edge/.style={draw,line width=5pt,-,red!50},
ignored edge/.style={draw,line width=5pt,-,black!20}
}

%Start of graph
\begin{tikzpicture}[scale=.7, auto,swap]
\foreach \pos/\name/\txt in {{(0,0)/a/\alpha},{(2,0)/b/\beta},{(3,2)/c/\gamma},{(2,4)/d/\delta},{(0,4)/e/\epsilon},{(-1,2)/f/\zeta}}
{
\node[vertex] (\name) at \pos {$\txt$};
}

\foreach \pos/\name in
{{(-1,-1)/1},{(-2,-2)/2},{(3,-1)/3},{(4,-2)/4},{(4,2)/5},
{(5,2)/6},{(-2,2)/7},{(-3,2)/8},{(-1,5)/9},{(-2,6)/10},{(3,5)/11},
{(4,6)/12}}
\node[vertex] (\name) at \pos {$\name$};

% Connect vertices with edges
\foreach \source/ \dest /\weight in {a/b/, b/c/, c/d/, d/e/,
e/f/,f/a/,a/1/,1/2/,b/3/,3/4/,c/5/,5/6/,f/7/,7/8/,e/9/,9/10/,d/11/,11/12/}
\path[edge] (\source) -- node[weight] {$\weight$} (\dest);

\end{tikzpicture}
\end{frame}
\end{document}

• @BrianNugent one way to appreciate the answer is to accept it by clicking on the checkmark on the left of the answer. The second way is to upvote it. – CroCo Aug 17 '17 at 1:24