Assigning a range of values to a variable in tikz - latex

Question

I would like to assign a range of values to a variable in LaTeX to be used in a loop within a tikzpicture environment.
In the below code I would like to replace these lines
\begin{tikzpicture}
\foreach \x in {1, 3, 5, 7}
\foreach \y in {2, ..., 5}{
with something like
first_range = {1, 3, 5, 7}
second_range = {2, ..., 5}
\begin{tikzpicture}
\foreach \x in first_range
\foreach \y in second_range{
A complete runnable code section is below:
\documentclass{article}
\usepackage{tikz}
\usepackage{ifthen}
\begin{document}
\begin{tikzpicture}
\foreach \x in {1, 3, 5, 7}
\foreach \y in {2, ..., 5}{
\ifthenelse{\(\x=1 \OR \x=7\) \AND \y = 3}{
%\filldraw[fill=white] (\x, \y) circle (0.2);
\node[] at (\x, \y) {\vdots};
}{
\filldraw[fill=red] (\x, \y) circle (0.2);
}
}
\end{tikzpicture}
\end{document}

Answer 1

You can store the list in a macro:
\documentclass{article}
\usepackage{tikz}
\usepackage{ifthen}
\def\first{1, 3, 5, 7}
\def\second{2, ..., 5}
\begin{document}
\begin{tikzpicture}
\foreach \x in \first
\foreach \y in \second {
\ifthenelse{\(\x=1 \OR \x=7\) \AND \y = 3}{
%\filldraw[fill=white] (\x, \y) circle (0.2);
\node[] at (\x, \y) {\vdots};
}{
\filldraw[fill=red] (\x, \y) circle (0.2);
}
}
\end{tikzpicture}
\end{document}