Cfrgtkky

I already have a code that draws a regular hexagon the following way

begin{tikzpicture}[every node/.style={draw,shape=circle,fill=blue}]

path (0,0) node (p0) {}

(-1.5,-1) node (p1) {}

(-1.5,-2.5) node (p2) {}

(1.5,-2.5) node (p3) {}

(1.5,-1) node (p4) {}

(0,-3.5) node (p5) { };

draw (p0) -- (p1)

(p0) -- (p1)

(p0) -- (p2)

(p0) -- (p3)

(p0) -- (p4)

(p0) -- (p5)

(p1) -- (p2)

(p1) -- (p3)

(p1) -- (p4)

(p1) -- (p5)

(p2) -- (p3)

(p2) -- (p4)

(p2) -- (p5)

(p3) -- (p4)

(p3) -- (p5)

(p4) -- (p5);

end{tikzpicture}

But Now I need to remove one of the points and to draw a regular pentagon the same way. So I need to remove (P5) and to recalibrate all other points (change their coordinates) But I don't need to change the code much.

Is there a way to do it by just slightly changing my code here. ?

You can use the geometric shapes given by the shapes.geometric library

usetikzlibrary{shapes.geometric}



begin{tikzpicture}[mystyle/.style={draw,shape=circle,fill=blue}]

defngon{5}

node[regular polygon,regular polygon sides=ngon,minimum size=3cm] (p) {};

foreachx in {1,...,ngon}{node[mystyle] (px) at (p.corner x){};}

foreachx in {1,...,numexprngon-1relax}{

  foreachy in {x,...,ngon}{

    draw (px) -- (py);

  }

}

end{tikzpicture}

For ngon being 9

For fun, a short code with pst-poly gets the desired result:

documentclass[svgnames]{standalone}



usepackage{pst-poly}

usepackage{auto-pst-pdf}

begin{document}



psset{unit=3.5cm, dimen=middle, linejoin=1, dotsize=12pt}

begin{pspicture}(-1,-1)(1,1)

    providecommand{PstPolygonNode}{psdots[dotsize=12pt, linecolor=SteelBlue](1;INode)

    }

    rput(0,0){PstPentagon[PolyName=A, linecolor=LightSteelBlue, linewidth=1.2pt] }

    rput(0,0){PstPentagon[PolyName=A, PolyOffset=2] }

end{pspicture}



end{document}

Maybe you like the following (based on (Thruston comment) rude solution (still need some manual calculation):

documentclass[border=3mm,tikz]{standalone}



begin{document}

begin{tikzpicture}[every node/.style={draw,shape=circle,fill=blue,text=white}]

    foreach i [count=ii from 0] in {90,150,...,390}

path (i:32mm) node (pii) {ii};

    foreach x in {0,...,5}

        foreach y in {x,...,5}

draw (py) -- (px);

    end{tikzpicture}

end{document}

For change number of nodes you need to determine start angle and manually determine next and final angle of node position.

Number in nodes are only informative, you can erase it.

Upgrade: An improved version, which itself calculate all necessary data from given number of nodes ans angle of the first node position:

documentclass[border=3mm,tikz]{standalone}



begin{document}

begin{tikzpicture}[

 every node/.style={draw,shape=circle,fill=blue,text=white}]

%%%% variable data data

defnumpoly{8}%number of nodes

defstartangle{30}%direction of the first node

defpradious{33mm}

%------- calculations of the positions angles

pgfmathparse{int(startangle+360/numpoly)}%

    letnextangle=pgfmathresult

pgfmathparse{int(startangle-360/numpoly+360)}%

    letendtangle=pgfmathresult

%--- nodes

    foreach i [count=ii from 1] in {startangle,nextangle,...,endtangle}

path (i:pradious) node (pii) {ii};

%--- interconnections

    foreach x in {1,...,numpoly}

        foreach y in {x,...,numpoly}

draw (py) -- (px);

    end{tikzpicture}

end{document}

With selection node numbers = 8 and the first node ias in direction 30 degrees, code we obtain:

One short tikz code without use of a library.

documentclass[border=7mm]{standalone}

usepackage{tikz}

begin{document}

foreach n in {3,...,7}

  tikzforeach i in {1,...,n}

    fill (i*360/n:1) coordinate (ni) circle(2 pt)

      ifnum i>1 foreach j in {i,...,1}{(ni) edge (nj)} fi;

end{document}

With the PGF graph drawing stuff (compile with lualatex):

documentclass[border=5]{standalone}

usepackage{tikz}

usetikzlibrary{graphs,graphs.standard}

tikzgraphsset{declare={polygon_n}{[clique]foreachx intikzgraphV{x/}}}

begin{document}

foreach n in {3,...,7}

  tikzgraph [clockwise, nodes={circle, fill=blue, inner sep=1}] 

    { polygon_n [n=n] };

end{document}

Here is a version in Metapost for comparison. Something of an exercise in loops.

prologues := 3;

outputtemplate := "%j%c.eps";

vardef polygon(expr n) = for t=0 step 360/n until 359: right rotated t -- endfor cycle enddef;

beginfig(1);

path p; 

for n=3 upto 7:

  p := polygon(n) scaled 20 shifted (n*48,0);

  for i=1 upto length p:

    for j=i+1 upto length p:

      draw point i of p -- point j of p;

    endfor

  endfor

  for i=1 upto length p:

    fill fullcircle scaled 3 shifted point i of p withcolor .67 red;

  endfor

endfor

endfig;

end