How to connect nodes using \draw

Question

I’m trying to draw a structure like that in Latex and I’m having a hard time. I know how to draw nodes using \node and how to draw arcs using \draw but I can’t connect the two.

Answer 1

In order to help you starting with TikZ, here's a quick solution that reproduce your hand drawn design. Feel free to adapt it.

In the future, please consider adding a minimal working example (MWE) that illustrates your problem, starting with \documentclass{...} and ending with \end{document}.

\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{chains}
\begin{document}
    \begin{tikzpicture}[
        start chain=going base right,
        node distance=2cm,
        every on chain/.append style=
            {draw = violet,
            circle,
            inner sep=0pt,
            minimum size=1cm,
            line width=1pt,
            font=\sffamily},
        myedge/.style={line width=1pt, violet}]
    \foreach \i in {1,...,6}
        \node[on chain] (\i) {\i};

    \foreach \i in {1,...,5}
        {
        \pgfmathtruncatemacro{\j}{\i+1}
        \draw[myedge] (\i) -- (\j);
        }

    \draw[myedge]   (1) to [out=90, in=0] ++(-2,3)
                    (2) to [out=90, in=180] ++(2,3)
                    (3) to [out=90, in=90, looseness=1.5] (4)
                    (5) to [out=90, in=180] ++(2,3);
\end{tikzpicture}

\end{document}

Answer 2

A wee bit variation of nice @SebGlaw answer:

\documentclass[border=3.141592]{standalone}
\usepackage{tikz}
\usetikzlibrary{chains,
                positioning}
\begin{document}
    \begin{tikzpicture}[
node distance = 2cm, on grid, 
  start chain = going right,   %
vertex/.style = {circle, draw = blue, thick,
                 minimum size=1em, 
                 font=\sffamily,
                 on chain, join = by arr},
   arr/.style = {draw=blue, semithick},

                        ]                        ]
    \foreach \i in {1,...,6}
\node[vertex] (\i) {\i};
\draw[arr]  (1) edge [out=90, in=0]   ++(-2,3)
            (2) edge [out=90, in=180] ++( 2,3)
            (3) edge [out=90, in=90,
                      min distance=15mm] (4)
            (5) edge [out=90, in=180] ++(2,3);
    \end{tikzpicture}
\end{document}

Answer 3

Here is the way a beginner might approach this:

First, place the nodes at your desired coordinates using the \node command. Then use \draw to connect nodes as you wish. The to[out= , in=] describes the angle out and the angle in to get curved lines. Finally, ++(x,y) describes relative coordinates (right x, up y) from the node.

\documentclass{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[every node/.style={circle, draw=blue, thick, inner sep=5pt}]
\node at (2,0)(A1){1};
\node at (4,0)(A2){2};
\node at (6,0)(A3){3};
\node at (8,0)(A4){4};
\node at (10,0)(A5){5};
\node at (12,0)(A6){6};
\draw[thick, blue] (A1)--(A2)--(A3)--(A4)--(A5)--(A6) 
    (A3) to[out=90, in=90] (A4)
    (A1) to[out=90, in=0] ++(-1,2)
    (A2) to[out=90, in=180] ++(1,2)
    (A5) to[out=90, in=180] ++(1,2);
\end{tikzpicture}
\end{document}