tikz: Label number of edges

In the following picture there are multiple edges between two vertices. But I am able to draw single edge. So I want to label the number of edges. How can I do it? For example there are $3$ edges between $1$ and $4$. How can I label $3$?

$\begin{tikzpicture}[scale=3, every loop/.style={}] \vertex[fill] (1) at (.5, 1) [label=above: 1] {}; \vertex [fill](2) at (0,.5) [label=left: 2] {}; \vertex[fill] (3) at (.5,0) [label=above: 3]{}; \vertex[fill] (4) at (1,0) [label=above: 4] {}; \vertex[fill] (5) at (1.5, 0.5) [label=right: 5] {}; \vertex [fill](6) at (1,1) [label=left: 6] {}; \draw (1,1) to[in=-50,out=-130,loop] (1,1); \path (1) edge (4) (1) edge (4) (1) edge (4) (1) edge (2) (2) edge (4) (2) edge (5) (3) edge (5) (3) edge (6) ; \end{tikzpicture}$
• (1) edge node [above] {label} (4), or with use quotes library and (1) edge ["label"] (4). if you will extend your code sniped to complete compilable document, we can simply show this on your picture example. welcome to tex.se! – Zarko Apr 28 at 13:23
• Thank you very much. But when I label all edges the numbers are not understandable for which edge it is defined. I mean it is not understandable that for which edges the labelling is done. @Zarko – a.nayek Apr 28 at 13:26
• well, this is not latex problem :-). please consider my ask and extend your code snippet to complete small document beginning with \documentclass and ending with \end{document} which we can test and than make suggestion how to place your edge labels. – Zarko Apr 28 at 13:30
• (2) edge["e"{swap,pos=.2}] (4) for example will move the node to the other side of the line (swap does that) and to 20% along the line from 2 to 4, instead of halfway (pos=0.2 does that). (By the way, @Zarko how is the positioning of the edge labels not a latex problem?) – Torbjørn T. Apr 29 at 20:51
• @TorbjørnT., how to write edges' labels are LaTeX problem and I give him a suggestion how to write them ... however, how are vertex placing and edges labels overlaps is image design problem. since I can't test his code and see how it looking, I can't help him further. So I ask him for MWE. and this ask is not LaTeX problem. – Zarko Apr 30 at 6:16

probably you looking for the following: since you not provide complete small document, which gives information what is \vertex, i reconstruct own code, for which i hope that is similar to what you like to have. in this I made to important changes:

• remove scale and accordingly multiply each coordinate
• reduce font size for edge labels
• define positions for labels so, that they not overlap

\documentclass[12pt,tikz, margin=3mm]{standalone}
\usetikzlibrary{arrows.meta,
quotes}

\begin{document}
\begin{tikzpicture}[
vertex/.style = {circle, fill, inner sep=2pt, outer sep=0pt},
every edge quotes/.style = {auto=left, sloped, font=\scriptsize, inner sep=1pt}
]
\node[vertex] (1) at (1.5,3)     [label=above: 1] {};
\node[vertex] (2) at (0,1.5)     [label=left: 2]  {};
\node[vertex] (3) at (1.5,0)     [label=left: 3]  {};
\node[vertex] (4) at (3,0)       [label=right: 4] {};
\node[vertex] (5) at (4.5,1.5)   [label=right: 5] {};
\node[vertex] (6) at (3,3)       [label=above: 6] {};
%
\path   (1) edge [pos=.35, "a"] (4)
(1) edge ["b"]  (2)
(2) edge ["c"]  (4)
(2) edge [pos=.35, "d"]  (5)
(3) edge [in=-50,out=-130, looseness=12] (3)
(3) edge ["e"]  (5)
(3) edge [pos=.75, "f"]  (6);
\end{tikzpicture}
\end{document}

addendum: an alternative code, slightly shorter, using the positioning library:

\documentclass[tikz, margin=3mm]{standalone}
\usetikzlibrary{arrows.meta,
positioning,
quotes}

\begin{document}
\begin{tikzpicture}[
node distance = 11mm and 11mm,
dot/.style = {circle, fill, inner sep=2pt, outer sep=0pt,
label=#1, node contents={}},
every edge quotes/.style = {auto=left, sloped, font=\scriptsize, inner sep=1pt}
]
\node (1) [dot=above:1];
\node (2) [dot= left:2, below  left=of 1];
\node (3) [dot= left:3, below right=of 2];
\node (4) [dot=right:4,       right=of 3];
\node (5) [dot=right:5, above right=of 4];
\node (6) [dot=above:6, above  left=of 5];
%
\path   (1) edge [pos=.35, "a"] (4)
(1) edge ["b"]  (2)
(2) edge ["c"]  (4)
(2) edge [pos=.35, "d"]  (5)
(3) edge [in=-50,out=-130, looseness=12] (3)
(3) edge ["e"]  (5)
(3) edge [pos=.75, "f"]  (6);
\end{tikzpicture}
\end{document}