Ndtyjky

I'm relatively new to TikZ and I drew the following graph. However, there is some space around the filled black node. Is there a way to have the lines actually connecting with the node?

EDIT: I'm not sure why it doesn't compile and show the graph in here? Maybe someone could please help me with this?

documentclass{article}

usepackage{tikz}

begin{document}

begin{tikzpicture}[scale=0.8]

node (1) at (0.4, 2.2) [circle,draw] {1};

node (4) at (0.4, 0.6) [circle,draw] {4};

node (3) at (2.6, 0.6) [circle,draw] {3};

node (7) at (1.5,1.5) {};

node (2) at (2.6, 2.2) [circle,draw] {2};



fill (7) circle (2.5pt);



draw[-] (1) to (7);

draw[-] (4) to (7);

draw[-] (3) to (7);

draw[-] (2) to (7);



end{tikzpicture}

end{document}

You can control the space added with the inner sep key:

documentclass{article}

usepackage{tikz}

begin{document}

begin{tikzpicture}[scale=0.8]

node (1) at (0.4, 2.2) [circle,draw] {1};

node (4) at (0.4, 0.6) [circle,draw] {4};

node (3) at (2.6, 0.6) [circle,draw] {3};

node[inner sep=0pt] (7) at (1.5,1.5) {};

node (2) at (2.6, 2.2) [circle,draw] {2};



fill (7) circle (2.5pt);



draw[-] (1) to (7);

draw[-] (4) to (7);

draw[-] (3) to (7);

draw[-] (2) to (7);



end{tikzpicture}

end{document}

You are already using circular node shapes, so why not here? And you can put the filled circle in the middle with barycentric cs: (but since you are naming the ones 1, 2, 3, 4, the syntax is here a bit amusing, which is the main reason why I am posting this ;-). And foreach can make your life easier.

documentclass{article}

usepackage{tikz}

begin{document}

begin{tikzpicture}[scale=0.8]

node (1) at (0.4, 2.2) [circle,draw] {1};

node (4) at (0.4, 0.6) [circle,draw] {4};

node (3) at (2.6, 0.6) [circle,draw] {3};

node (2) at (2.6, 2.2) [circle,draw] {2};

node[inner sep=2.5pt,circle,fill] (7) at (barycentric cs:1=1,2=1,3=1,4=1) {};



foreach X in {1,...,4}

{draw[-] (X) to (7);}



end{tikzpicture}

end{document}

documentclass{article}

usepackage{tikz}

begin{document}

begin{tikzpicture}[scale=0.8]

node (1) at (0.4, 2.2) [circle,draw] {1};

node (4) at (0.4, 0.6) [circle,draw] {4};

node (3) at (2.6, 0.6) [circle,draw] {3};

node (7) at (1.5,1.5) {};

node (2) at (2.6, 2.2) [circle,draw] {2};



node[circle, fill=black, draw=black, minimum size=2.5pt] (7) at (1.5, 1.4) {};



draw[-] (1) to (7);

draw[-] (4) to (7);

draw[-] (3) to (7);

draw[-] (2) to (7);



end{tikzpicture}

end{document}

You forgot begin{document} and you should use a node for the circle as well, where you specify the size and color in the node properties.

You can define (7) as coordinate instead of node to solve this.

documentclass[tikz,border=2mm]{standalone}

begin{document}

begin{tikzpicture}

node (1) at (0.4, 2.2) [circle,draw] {1};

node (4) at (0.4, 0.6) [circle,draw] {4};

node (3) at (2.6, 0.6) [circle,draw] {3};

coordinate (7) at (1.5,1.5) {};

node (2) at (2.6, 2.2) [circle,draw] {2};



fill (7) circle (2.5pt);



draw (1) to (7);

draw (4) to (7);

draw (3) to (7);

draw (2) to (7);

end{tikzpicture}

end{document}

using polar coordinates and foreach loop make your code simpler and shorter ...

documentclass[tikz, margin=3.141592mm]{standalone}



begin{document}

    begin{tikzpicture}[scale=0.8,

circ/.style = {circle, draw},

 dot/.style = {circle, fill, inner sep=2.5pt}

                        ]

node (n7) [dot]    {};

foreach i [count=ii] in {135, 45, 315, 225}

node (ii) [circ] at (i:16mm) {ii};

draw (1) -- (3)    (2) -- (4);

end{tikzpicture}

end{document}

I would like to join the celebration by offering an additional solution!

The middle node (7) is defined when drawing the first diagonal (1)--(3).

draw (1) -- (3) node [midway,fill] (7){};

I also factorized the style applied to the nodes with the key every node/.style={circle,draw}

documentclass{article}

usepackage{tikz}

begin{document}

begin{tikzpicture}[scale=0.8,every node/.style={circle,draw}]]

node (1) at (0.4, 2.2) {1};

node (4) at (0.4, 0.6) {4};

node (3) at (2.6, 0.6) {3};

node (2) at (2.6, 2.2) {2};

draw (1) -- (3) node [midway,fill] (7){};

draw (2) to (7)to (4);

end{tikzpicture}

end{document}