Cfrgtkky

I am having some problems with macro expansion in TikZ nodes. The MWE below is supposed to draw nodes at specified coordinates and display their coordinate rounded to the nearest number, but it shows the coordinates of the last node for both of them.

documentclass{article}



usepackage{pgfplots}

usepackage{xparse}



ExplSyntaxOn



tl_new:N x

tl_new:N x_round



NewDocumentCommand mynode { m } {

    tl_set:Nn x { 

        fp_eval:n { #1 } 

    }



    tl_set:Nn x_round { 

       fp_eval:n { round ( x ) } 

    }



    addplot [style={mark=none}] coordinates { ( x , x ) } node { x_round } ;

}



ExplSyntaxOff



begin{document}

    begin{tikzpicture}

        begin{axis}            

            mynode{1.1}

            mynode{2.2}

        end{axis}

    end{tikzpicture}

end{document}

I assume the problem is that the x_round is not expanded in the node until the end of the environments. How can I ensure x_round is expanded immediately?

I have noticed that replacing the command with

NewDocumentCommand mynode { m } {

    addplot [style={mark=none}] coordinates { ( #1 , #1 ) } node { fp_eval:n { round ( #1 ) }  } ;

}

does fix the problem, but for my real code, it is inadequate as the code is more complex.

You should use tl_set:Nx, but it's quite pointless anyway:

documentclass{article}



usepackage{pgfplots}

usepackage{xparse}



ExplSyntaxOn



NewDocumentCommand mynode { m }

 {

  addplot [style={mark=none}]

    coordinates { ( fp_eval:n { #1 } , fp_eval:n { #1 } ) }

    node { fp_eval:n { round(#1) } } ;

 }



ExplSyntaxOff



begin{document}



begin{tikzpicture}

  begin{axis}

    mynode{1.1}

    mynode{2.2}

  end{axis}

end{tikzpicture}



end{document}

Avoid names such as x and x_round, use the proper naming conventions.

You can use variables (here I use fp ones, but tl can be good as well, provided you set them with tl_set:Nx). However, text in the node has to be expanded before passing it to PGF:

documentclass{article}



usepackage{pgfplots}

usepackage{xparse}



ExplSyntaxOn



fp_new:N l_slo_coord_x_fp

fp_new:N l_slo_coord_x_round_fp



NewDocumentCommand mynode { m }

 {

  fp_set:Nn l_slo_coord_x_fp { #1 }

  fp_set:Nn l_slo_coord_x_round_fp { round ( l_slo_coord_x_fp ) }

  use:x

   {

    exp_not:N addplot [style={mark=none}]

      coordinates { ( fp_use:N l_slo_coord_x_fp , fp_use:N l_slo_coord_x_fp ) }

      node { fp_use:N l_slo_coord_x_round_fp } ;

   }

 }



ExplSyntaxOff



begin{document}



begin{tikzpicture}

  begin{axis}

    mynode{1.1}

    mynode{2.2}

  end{axis}

end{tikzpicture}



end{document}