TikZ loop avoiding values in a given list

Question

I would like to have a loop which avoids elements in a specified list, ideally something like this:

\def\list{{1,3,6}}
\foreach \i in {1,...,7} {
  if "\i not in \list" do {...} else do {... }
 }

which should do something for \i=2,4,5,7 but not for \i=1,3,6.

I am very new to TikZ, but still hope that it's clear what I'm asking ...

Answer 1

Something like this?

\newif\ifoneofthese
\oneofthesefalse
\foreach \i in {1,...,7}%
  {%
    \oneofthesefalse
    \foreach \j in {1,3,6}%
    {%
      \ifx\i\j \global\oneofthesetrue\fi
    }%
    \ifoneofthese\relax\else \i{} is not in the list. \fi
  }

EDIT

This works fine with a macro for the exclusion list:

\newcommand*\mylist{1,3,6}
\foreach \i in {1,...,7}%
  {%
    \oneofthesefalse
    \foreach \j in \mylist
    {%
      \ifx\i\j \global\oneofthesetrue\fi
    }%
    \ifoneofthese\relax\else \i{} is not in the list. \fi
  }

produces identical output to the original version:

Complete Code

\documentclass{article}
\usepackage{pgffor}
\begin{document}
\newif\ifoneofthese
\oneofthesefalse
\foreach \i in {1,...,7}%
  {%
    \oneofthesefalse
    \foreach \j in {1,3,6}%
    {%
      \ifx\i\j \global\oneofthesetrue\fi
    }%
    \ifoneofthese\relax\else \i{} is not in the list. \fi
  }
\newcommand*\mylist{1,3,6}
\foreach \i in {1,...,7}%
  {%
    \oneofthesefalse
    \foreach \j in \mylist
    {%
      \ifx\i\j \global\oneofthesetrue\fi
    }%
    \ifoneofthese\relax\else \i{} is not in the list. \fi
  }
\end{document}