Assign a color to a variable name in a newcommand

Question

I am writing a complex diagram using TikZ in which the colors used for certain nodes depend on the value of the input variable. I cannot use the color itself as an input variable as certain things other than a color also change.

I have not written this yet, so cannot provide a MWE, but the idea is:

1. Check the value of an input parameter (say #1) using \ifthenelse.
2. Assign some colors to a set of variable, say boxcolor=red!90!black,flatcolor=blue!30!green, juxtaposecolor=yellow if #1 takes one value, another set of the above colors if #1 takes another value.
3. Draw the diagram, using boxcolor, flatcolor, juxtaposecolor, etc. directly, and colors calculated based on them (boxcolor!40!flatcolor).

How do I do this inside a newcommand? Can color variables be first set in some way, and then used in some common code block that follows?

Answer 1

Is this the effect you want?

\documentclass[margin = 1cm]{standalone}
\usepackage{tikz}
\begin{document}
  \def\test#1{%
  \ifnum#1>10 %
    \colorlet{main}{red}%
  \else
    \ifnum#1>1 %
      \colorlet{main}{blue}%
    \else 
      \colorlet{main}{brown}%
    \fi 
  \fi 
  }

\begin{tikzpicture}
  \foreach \x in{-1,5,12}
  {
    \test{\x}
    \draw[main] (\x,0)circle(2);
  }  
\end{tikzpicture}
\end{document}

when #1 > 10 , main = red; and 1 < #1 <= 10, main = blue; else, main = brown.