Bdtyk

This question is related to Strange behavior in TikZ draw command but is not the same.

While working with coordinates and nodes in TikZ, I was expecting that:

  coordinate (x) at (4,0) node[right] {$x$};

  coordinate (y) at (0,3) node[above] {$y$}; 

and

  node[right] at (x) {$x$};

  node[above] at (y) {$y$};

would yield the same result. But they don't. I get the following output:

With coordinate (x) at (4,0) node[right] {$x$};, I meant, the system will create a node at (4,0) and will place the text $x$ to its right.

Based on the output, I see the text $x$ is placed at (0,0), with the above command.

Why does this happen.

MWE:

documentclass{article}

usepackage{tikz}

usetikzlibrary{intersections}

begin{document}

begin{tikzpicture}

  coordinate (x) at (4,0) node[right] {$x$};

  coordinate (y) at (0,3) node[above] {$y$};



  node[right] at (x) {$x$};

  node[above] at (y) {$y$};



  draw[<->,thick] (0,3) |- (4,0);

end{tikzpicture}

end{document} 

try the following:

documentclass{article}

usepackage{tikz}

%usetikzlibrary{intersections} not used in this mwe



begin{document}

begin{tikzpicture}

  coordinate[label=right:$x$] (x) at (4,0);

  coordinate[label=above:$y$] (y) at (0,3);



  draw[<->,thick] (y) |- (x);

end{tikzpicture}

end{document}

In section 17.2.1 of the TikZ manual, the commands for such works are shown:

• 
  

  path ... node ... (1.1)

  
  
  

  or node ... (1.2)

  
  


• 
  

  path ... coordinate ... (2.1)

  
  
  

  or coordinate ... (2.2)

  
  

coordinate ... node ... are not present!

That is why coordinate (x) at (4,0) node[right] {$x$}; and node[right] at (x) {$x$}; don't give the same result. In fact, coordinate (x) at (4,0) node[right] {$x$}; is understood as

coordinate (x) at (4,0); 

path node[right] {$x$}; % (0,0) in case no coordinates are specified

That is why we get

with this code

documentclass[tikz]{standalone}

begin{document}

begin{tikzpicture}

coordinate (x) at (2,0) node[draw,right] {world};

fill (x) circle (1pt)

    (0,0) circle (1pt);

end{tikzpicture}

end{document}

and we get

with this code

documentclass[tikz]{standalone}

begin{document}

begin{tikzpicture}

node[draw] (x) at (2,0) {Hello} node[draw,right] {world};

fill (0,0) circle (1pt);

end{tikzpicture}

end{document}

So how to solve it? We can't combine (2.2) or (1.2) with ... node ..., but we can do it with (1.1) or (2.1):

path (4,0) coordinate (x) node[right] {$x$};

Remember that draw, fill, filldraw... are all daughters of path, so they are all valid. But node and coordinate are not.

I found this using the draw powerful trick :)

It doesn't give you the expected result because the syntax is not appropriate. (At which level do you expect an explanation? Does it help that in coordinate (x) at (4,0) node[right] {$x$}; at (4,0) got "absorbed" by coordinate (x) so that TikZ adds the default coordinate (0,0) to interpret node[right] {$x$}?) You can condense all statements to one line.

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

begin{document}

begin{tikzpicture}

  draw[<->,thick] (0,3) coordinate (y) node[above] {$y$} |- (4,0) coordinate (x)  node[right] {$x$};

end{tikzpicture}

end{document}