Gsyfuy

I am still new to using Tikz... I am trying to draw a wheel-like graph using TikZ. I have the basic graph done, but it is not turning out how I expected it to. The edges in my graph aren't centered/lined up well.

The edges seem to be following the coordinates rather than drawing a shortest-path straight line between the nodes stopping at their circle representations. Some of the edges are fine (like v1 to v2, v1 to v6, ...) but some others aren't (like v2 to v3).

Here is my code for the TikZ picture, and an image showing what I am getting.

begin{tikzpicture}[auto, scale=0.9]

tikzstyle{vertex}=[draw, circle, inner sep=0.55mm]

node (v1) at (0,0) [vertex] {};

node (v2) at (1,0) [vertex] {};

node (v3) at  (1.5,-1) [vertex] {};

node (v4) at (1,-2) [vertex] {};

node (v5) at (0,-2) [vertex] {};

node (v6) at (-.5,-1) [vertex] {};

node (v7) at  (.5,-1) [vertex, fill=blue] {};



foreach x in {2, 3, 4, 5, 6, 7}{

    pgfmathsetmacroy{x - 1}

    draw (vy) to (vx);

}

draw (v6) to (v1);

draw (v5) to (v7);

draw (v4) to (v7);

draw (v3) to (v7);

end{tikzpicture}

tikzstyle is deprecated and the issue is that pgfmathsetmacro does not yield integers, but something like 2.0, where .0 gets interpreted as node anchor.

documentclass[tikz,border=3.14mm]{standalone}

begin{document}

begin{tikzpicture}[auto, scale=0.9]

tikzset{vertex/.style={draw, circle, inner sep=0.55mm}}

node (v1) at (0,0) [vertex] {};

node (v2) at (1,0) [vertex] {};

node (v3) at  (1.5,-1) [vertex] {};

node (v4) at (1,-2) [vertex] {};

node (v5) at (0,-2) [vertex] {};

node (v6) at (-.5,-1) [vertex] {};

node (v7) at  (.5,-1) [vertex, fill=blue] {};



foreach x [remember =x as lastx (initially 1)] in {2, 3, 4, 5, 6, 7}{

    draw (vlastx) to (vx);

}

draw (v6) to (v1);

draw (v5) to (v7);

draw (v4) to (v7);

draw (v3) to (v7);

end{tikzpicture}

end{document}

That's because the calculation of y doesn't give an integer. There are two possibilities:

• the first is to use the macro pgfmathtruncatemacro instead of pgfmathsetmacro
  


• the second is to evaluate y within the foreach loop itself

documentclass[tikz,border=5mm]{standalone}



usetikzlibrary{calc}



begin{document}

begin{tikzpicture}[auto, scale=0.9]

tikzstyle{vertex}=[draw, circle, inner sep=0.55mm]

node (v1) at (0,0) [vertex] {};

node (v2) at (1,0) [vertex] {};

node (v3) at  (1.5,-1) [vertex] {};

node (v4) at (1,-2) [vertex] {};

node (v5) at (0,-2) [vertex] {};

node (v6) at (-.5,-1) [vertex] {};

node (v7) at  (.5,-1) [vertex, fill=blue] {};



foreach x[evaluate=x as y using int(x-1)] in {2, 3, 4, 5, 6, 7}{

    %pgfmathtruncatemacroy{x - 1}

    draw (vy) to (vx);

}

draw (v6) to (v1);

draw (v5) to (v7);

draw (v4) to (v7);

draw (v3) to (v7);

end{tikzpicture}

end{document}

To get it more wheel like you can use polar coordinates, like (1,45) to draw a node at distance 1 and 45 degrees from origin. Here is an alternative version with a variable number of nodes. Change the number in numNodes{6} to change the number of nodes n the circle.

documentclass[border=5mm]{standalone}

usepackage{tikz}

begin{document}

begin{tikzpicture}[

  auto, 

  scale=0.9,

  vert/.style={draw, circle, inner sep=0.55mm,fill=white}

  ]

  newcommandnumNodes{6}

  node[vert,fill=blue] (vC) at (0,0){};

  draw (0:1) node[vert](v0) {}

  foreach n [evaluate = n as deg using {n*360/numNodes}] in {1,2,...,numNodes}{

    -- (deg:1) node[vert](vn) {}

  };

  foreach n in {0,3,4,5}{

    draw (vC) -- (vn);

  }

end{tikzpicture}



end {document}

maybe you will like:

documentclass[tikz,border=5mm]{standalone}

usetikzlibrary{shapes.geometric}



begin{document}

begin{tikzpicture}[

vertex/.style = {circle, draw, fill=#1, inner sep=0.5mm}

                    ]

%

node (s) [regular polygon,regular polygon sides=6,

           draw, minimum size=20mm, above] at (0.5,-2) {};

draw (s.corner 3) -- (s.corner 6);

node (c) [vertex=blue] at (s.center) {};

%

foreach i in {1,...,6}{node (si) [vertex=white] at (s.corner i) {}; }



draw (c) -- (s4)

      (c) -- (s5);

end{tikzpicture}

end{document}