How to shift edge labels along edges in tkz-graph?

Question

Using tkz-graph package I often feel the need to move a little bit the labels on the edges, that are always positioned midway the edge. In this example I would move the label 0.5 from node a to node d closer to node d to avoid intersection with a red box. Here a MWE:

\documentclass[border=10pt]{standalone}
\usepackage{tkz-graph}
\usetikzlibrary{fit}
\thispagestyle{empty}
\begin{document}
    \begin{tikzpicture}
        \GraphInit[vstyle=Normal]
        \SetGraphUnit{1.5}
        \Vertices{circle}{a,b,c,d,e}
        \Edge[label=1](a)(b)
        \Edge[label=2](a)(c)
        \Edge[label=0.5](a)(d)
        \Edge[label=3](a)(e)
        \node[draw=red!50,rounded corners=5mm,fit=(b.north) (a.south) (c.west) (a.east)](BORD) {};
    \node[right of=BORD,anchor=west,inner sep=1cm]{$\mathcal{G}$};
    \end{tikzpicture}
\end{document}

This is the result:

How to mode the 0.5 label along the edge and not always in the center?

Answer 1

The \Edge macro is only syntactic sugar for basic TikZ which draw a path and places a node on it. Nodes on paths can receive the pos key to indicate at what fraction the node is to be placed. To set node option in \Edge you have to wrap them in the style option, i.e.

\Edge[label=0.5,style={pos=.3}](a)(d)

to place the node at one third of the path starting from (a). For your example I chose pos=.25.

\documentclass[border=10pt]{standalone}
\usepackage{tkz-graph}
\usetikzlibrary{fit}
\begin{document}
\begin{tikzpicture}
  \GraphInit[vstyle=Normal]
  \SetGraphUnit{1.5}
  \Vertices{circle}{a,b,c,d,e}
  \Edge[label=1](a)(b)
  \Edge[label=2](a)(c)
  \Edge[label=0.5,style={pos=.25}](a)(d)
  \Edge[label=3](a)(e)
  \node[draw=red!50,rounded corners=5mm,fit=(b.north) (a.south) (c.west) (a.east)](BORD) {};
  \node[right of=BORD,anchor=west,inner sep=1cm]{$\mathcal{G}$};
\end{tikzpicture}
\end{document}