Trjtdtk

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:

documentclassarticle
usepackagetikz
usetikzlibraryintersections
begindocument
begintikzpicture
 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);
endtikzpicture
enddocument 

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
begindocument
begintikzpicture
 draw[<->,thick] (0,3) coordinate (y) node[above] $y$ |- (4,0) coordinate (x) node[right] $x$;
endtikzpicture
enddocument 

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 for the same job! In fact, since coordinate is the same as path coordinate so coordinate (x) at (4,0) node[right] $x$; is understood as

path coordinate (x) at (4,0); % or `coordinate (x) at (4,0);
path node[right] $x$; % (0,0) in case no coordinates are specified

This makes the outputs of coordinate (x) at (4,0) node[right] $x$; and node[right] at (x) $x$; not the same at all.

That is why we get

with this code

documentclass[tikz]standalone
begindocument
begintikzpicture
coordinate (x) at (2,0) node[draw,right] world;
fill (x) circle (1pt)
 (0,0) circle (1pt);
endtikzpicture
enddocument

and we get

with this code

documentclass[tikz]standalone
begindocument
begintikzpicture
node[draw] (x) at (2,0) Hello node[draw,right] world;
fill (0,0) circle (1pt);
endtikzpicture
enddocument

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 – they are less general versions of path..

I found this using the draw powerful trick :)

try the following:

documentclassarticle
usepackagetikz
%usetikzlibraryintersections not used in this mwe

begindocument
begintikzpicture
 coordinate[label=right:$x$] (x) at (4,0);
 coordinate[label=above:$y$] (y) at (0,3);

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

addendum:
as response to Martin Argerami coments below my answer, who is convinced that my answer not address op problem (and consequently he apparently down vote it, for what i'm very grateful. his message is very clear: don't show people some possible solution for which they not explicit ask). however let me note some my view on the problem:

• in answer i only suggest to see if my suggestion can help to op


• it solve the problem of placement of coordinate labels (in this is all about it, isn't it?)


• if the answer is not helpful, op can select one from other two answers as the best one and accept it.


• to be strict to Martins' consideration, that he should down vote many other answers, which try show another possibility to achieve op goal (nice picture, table, etc) or is written as exercise (personal or for op) ...


• on the end, i'm still convinced, that my answer not harm anyone, it only show another way how to draw coordinates shown in op mwe. is this worth for down voting it?