How to evaluate tikz expression before printing as text?

Question

Edit: In response to the comments, the question has been edited to include the MWE. The accepted answer (by Gonzalo) is still valid.

Here's my code:

\documentclass{article}


% *** MISC UTILITY PACKAGES ***
\usepackage{graphicx}
\usepackage[caption=false]{subfig}%The caption option has been disabled
%to avoid conflict with the IEEEtran class file.
\usepackage{tikz}

% *** MATH PACKAGES ***
\usepackage[cmex10]{amsmath}
\usepackage{amssymb}

\begin{document}
\begin{figure}[!t]
    \centering
\begin{tikzpicture} 
\node[anchor=south west, inner sep = 0] (image) at (0,0)
{\includegraphics[width=8cm]{Tulips.jpg}};
\begin {scope}[x={(image.south east)},y={(image.north west)}]
   \fill [white] (0,0) rectangle (1,1);
   \foreach \y in {0,1,...,8} { \node [anchor=east] at (0.09,0.07+0.88*\y/8) {\small {-5+5*\y}}; }
\end {scope}
\end{tikzpicture}
\caption{Nothing} 
\label{nothing}
\end{figure}
\end{document}

Here's the result:
enter image description here

I wanted the series to appear as {-5,0,5,...35}. What's being shown is {-5+5*0,-5+5*1,-5+5*2,...-5+5*8}.

How to evaluate the series before it gets printed as text?

Please, please, please: Post full minimal documents instead of just snippets. Finding answers is fun, completing documents is not. — Jake, Sep 27 '12 at 18:12
I guess you did not use standalone class for each diagram you want to draw. — kiss my armpit, Sep 27 '12 at 18:33
@GonzaloMedina Thanks! At Jake and Andrew: Since this wasn't a bug I wanted to know the command that could do the job (in hindsight I can say it's \yeval). I thought of it more as a theory question. I have learnt a lot from answers you guys have posted (perhaps more than any book) and I agree that MWEs help. People having similar problems can simply copy the MWEs to understand Latex. Hence I have modified question to include the MWE. Sincerest apologies for not including it to begin with. — Shashank Sawant, Sep 27 '12 at 19:14
@ShashankSawant: I have resorted to using \pgfmathsetmacro{\<name>}{<expression>} to compute expression and has found that quite useful. The evaluate= is clearly better for this case, but you should keep \pgfmathsetmacro in mind. — Peter Grill, Sep 27 '12 at 20:45

Gonzalo Medina · Accepted Answer · 2012-09-27T19:15:09.107

You can use the evaluate=<variable> as <macro> using <formula> syntax:

\documentclass{scrartcl}
\usepackage{tikz,pgf}
\usepackage{graphicx}

\begin{document}

\begin{tikzpicture} 
\node[anchor=south west, inner sep = 0] (image) at (0,0)
{\includegraphics[width=8cm]{cat}};
\begin {scope}[x={(image.south east)},y={(image.north west)}]
  \draw [help lines,lime,xstep=.01,ystep=.01] (0,0) grid (1,1);
  \draw [help lines,orange,xstep=.05,ystep=.05] (0,0) grid (1,1);
  \draw [help lines,red,xstep=.1,ystep=.1] (0,0) grid (1,1);
  \foreach \x in {0,1,...,9} { \node [anchor=north] at (\x/10,0) {0.\x}; }
  \foreach \y in {0,1,...,9} { \node [anchor=east] at (0,\y/10) {0.\y}; }

   \fill [white] (0,0) rectangle (1,1);
  \foreach \y [evaluate=\y as \yeval using -5+5*\y] in {0,...,8} { \node [anchor=east,font=\tiny] at (0.09,0.07+0.88*\y/8) {\pgfmathtruncatemacro{\yet}{\yeval}\yet}; }
\end {scope}
\end{tikzpicture}

\end{document}

enter image description here

score 5 · Answer 2 · answered Sep 27 '12 at 19:24

Answer to the modified question:

\documentclass{article}


% *** MISC UTILITY PACKAGES ***
\usepackage{graphicx}
\usepackage[caption=false]{subfig}%The caption option has been disabled
%to avoid conflict with the IEEEtran class file.
\usepackage{tikz}

% *** MATH PACKAGES ***
\usepackage[cmex10]{amsmath}
\usepackage{amssymb}

\begin{document}
\begin{figure}[!t]
    \centering
\begin{tikzpicture} 
\node[anchor=south west, inner sep = 0] (image) at (0,0)
{\includegraphics[width=8cm]{Tulips.jpg}};
\begin {scope}[x={(image.south east)},y={(image.north west)}]
   \fill [white] (0,0) rectangle (1,1);
%   \foreach \y in {0,1,...,8} { \node [anchor=east] at (0.09,0.07+0.88*\y/8) {\small {-5+5*\y}}; }
\foreach \y [evaluate=\y as \yeval using -5+5*\y] in {0,...,8} { \node [anchor=east,font=\small] at (0.09,0.07+0.88*\y/8) {\yeval}; }
\end {scope}
\end{tikzpicture}
\caption{Nothing} 
\label{nothing}
\end{figure}
\end{document}

The output looks like this: enter image description here

How to evaluate tikz expression before printing as text?

2 Answers2

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