tkz-graph : inconsistency between edge and loop

Question

I'm discovering the great package tkz-graph and I experience some trouble-shotting with the loop macro.

There some inconsistency — in my opinion — between the loop macro and the edge macro. For exemples, in this MWE, the labels of the edges are note placed in the same way, the loop has an array and not the edge and the syntax \( \) for math-mode works only in the case of the loop.

\documentclass{minimal}
\usepackage{fixltx2e}
\usepackage{tkz-graph}
\begin{document}
\begin{tikzpicture}[scale=1]
  \Vertex{A}
  \Vertex[x=2,y=0]{B}
  \Loop[dist=1.5cm,dir=WE,label=\(x\)](A)
  \Edges[label=$y$](A,B)
\end{tikzpicture}
\end{document}

Moreover, the macro \tikzset{EdgeStyle/.append style = …}doesn't work for loops and I did not find a solution in the user manual. For exemple, \tikzset{EdgeStyle/.append style ={->}} doesn't use the same arrow tip for the edge and for the loop.

Finally, the use of style={->} produces different results in the loop that in the edge (the path is thicker in the edge).

Here is a picture off the exemple, with \tikzset{EdgeStyle/.append style ={->}} :

Answer 1

Sorry for the french documentation but with the next version I will try to write a english version. The question is about tkz-graphand not tkz-bergeand tkz-bergehas an english doc !!

A last detail before my answer, I'm not happy about the options(styles) of these packages because I wrote them with xkeyval and it's difficult to get the same options than Tikz. I will write the next version with pgfkeys.

Now the problem appears because there are a lot of method to change the styles. EdgeStyleis used to modify a global style for edges, LoopStyle is a global style for loops and style is local; Loop first looks at EdgeStyle, then at LoopStyle and at the end applies a local style if this style exists. For the labels, you have LabelStyle and then labelstyle

The code is

\def\tkzGR@loop[#1](#2){%
\setkeys[GR]{loop}{#1}%
\protected@edef\@tempa{%
\noexpand \draw[\cmdGR@loop@color] (#2)%
  edge [EdgeStyle,LoopStyle,\cmdGR@loop@style]%
  node [LabelStyle,\cmdGR@loop@labelstyle]%
  {\cmdGR@loop@label} (#2)}\@tempa;%
}%

A possible solution is

\documentclass{minimal}
\usepackage{fixltx2e}
\usepackage{tkz-berge}

\tikzset{LabelStyle/.style= {fill=yellow}}

\begin{document}
\begin{tikzpicture}[scale=1]
  \Vertex{A}
  \Vertex[x=2,y=0]{B}     
  \Loop[dist=1.5cm,dir=WE,label=\(x\),
        labelstyle={left=12pt,color=red,fill=white,draw}](A)
  \Edges[label=$y$](A,B)
\end{tikzpicture}
\end{document} 

I agree if you find the styles unclear or confused but I will make something better with pgfkeysin the next version. I need to make the versions compatible because tkz-graph is used by lot of people.

The first solution of Count Zero is fine too

Update : Another solution is to define a personal style and to use only Tikzto draw the loops. It's always possible to use tikz.

Answer 2

You have two options:

1. either you put a white (or other color, but not transparent) background to your node:

   \documentclass{minimal}
   \usepackage{fixltx2e}
   \usepackage{tkz-berge}
   
   \tikzset{LabelStyle/.style= {fill=white}}
   
   \begin{document}
   \begin{tikzpicture}[scale=1]
     \Vertex{A}
     \Vertex[x=2,y=0]{B}
     \Loop[dist=1.5cm,dir=WE,label=\(x\)](A)
     \Edges[label=$y$](A,B)
   \end{tikzpicture}
   \end{document}
   

2. or you displace the label (this is probably a less elegant hack):

   \documentclass{minimal}
   \usepackage{fixltx2e}
   \usepackage{tkz-berge}
   
   \begin{document}
   \begin{tikzpicture}[scale=1]
     \Vertex{A}
     \Vertex[x=2,y=0]{B}
     \tikzset{LabelStyle/.style= {xshift=-.25cm}}
     \Loop[dist=1.5cm,dir=WE,label=\(x\)](A)
     \tikzset{LabelStyle/.style= {xshift=0cm}}% set shift back to original (0) value
     \Edges[label=$y$](A,B)
   \end{tikzpicture}
   \end{document}
   

whichever you prefer. :) Note that in both cases I fumbled with LabelStyle/.style=... not EdgeStyle.

EDIT: EdgeStyle takes a labelstyle parameter, which is basically the same as modifying directy the LabelStyle. Therefore I doubt there is another workaround.

PS: Too bad the documentation is only in French... I'm saying this because the tkz package family is asolutely terrific and in fact this language barrier prevents lots of people from using them.